As a (two months old) newbie, I just made a little graphic FAQ, to better understand the existing tutorial threads about HSPL and flashing Cooked ROMs. I believe it can very rapidly answers many newbie questions.
Part 1: Mini-Glossary
ROM (not to be confused with RAM, duh!)= Basically its the program that runs your phone. It includes the Windows Mobile (OS) + HTC Sense interface + Radio (not to be confused with FM Radio, duh!).
RAM = Random-access memory = The more RAM you have, the better you can launch and use programs at the same time (the so called "multitasking"). Its an hardware component that you are not able to change on a smartphone (as opposed to a computer, where you can buy and physically add more RAM). But... American T-Mobile HD2 will officially have 576 Mb of RAM. European HD2 officially has 448 Mb of RAM, which is already a lot, but the 2.06.50.4 or 2.07.50.27_2 radios seem to unlock extra RAM to a full 576 Mb, on some leaked ROMS.
OS = Operating System = The engine that controls the computer side of your HD2, meaning . Currently, all stock ROMs come with Windows Mobile 6.5 on HD2, but Microsoft is about to launch Windows Mobile 6.6, previously called 6.5.3 (maybe on March 2010) and Windows Mobile 7 (maybe late 2010 or early 2011). WM 6.6 will definitely be ported to HD2, but nobody knows for sure if WM 7 will be. Leaked version of 6.5.3 are already part of many cooked ROMs. It improves the use of Windows Mobile with touchscreens (understand: larger icons & larger menus).
Radio (not to be confused with FM Radio, duh!) = The program engine that controls the wireless connections of your HD2, meaning phone signal reception (GSM), data connections (2G, 3G, GPRS, HSDPA...), navigation (GPS), wifi and bluetooth. It also controls sound and camera. It is part of official ROMs and is issued by HTC. Radio version must be compatible with OS to work properly. It subsequently changes (improve or worsen) your battery life. You can actually install a specific radio without installing a whole ROM. You will need to use HSPL first, of course. You'll find all official and leaked Radio for HD2 in this thread. It has also be proven here that installing the 2.06.50.4 or 2.07.50.27_2 Radios can somehow "unlock" the full use of 576 Mb or RAM, instead of standard 448 Mb. No other radio (older or newer) has that ability. Note that the radio has to be installed along with some patch on the ROM to make it work.
Stock ROM = Shipped ROM = Official ROM available from the HTC website. Note that they are "region protected", so you can't install a stock ROM from another country or region, unless you HSPL your device. The same goes for the Official Hotfixes, they are also "region protected".
Carrier ROM = Official ROM designed by a carrier (T-mobile, Orange, Telstra, Vodafone, O²...), based on stock ROM, but slightly changed to install specific softwares or modify default softwares. Usually, these ROMs do not necessarily give better performances, but carriers design them to enable some specific uses on their network. Note that it is absolutely not necessary to have a carrier ROM to be able to use a specific network. Anyone can buy a SIM-unlock HD2, insert any SIM card and in during the first start, it will automatically download basic parameters to enable phone calls, SMS/MMS messages, data connection and so forth. You'll still need to enter the right parameters to enable email though.
Leaked ROM = Official ROM made by HTC, but not officially released and not completely debugged. You can call them "beta" versions. Even though HTC did not performed enough testing to make sure theses ROMs are bug-free, they are usually very useful for everyday use. When they get official released, they are eventually more stable and up-to-date. Oh, and how did they find their way on internet? Well, internet ways, like those celebrity sextapes :).
Cooked ROM = Custom ROM = ROM designed by someone ("experienced users"), usually based on stock ROM, but slightly changed to get better performances (tweaks, changed radio, changed Windows Mobile version) or prettier interface (example: changed sense interface, modified icons etc).
Chiefs = Cookers = it's the way we call people ("experienced users") who design cooked ROMs.
Install a ROM = Flash a ROM = Replacing one ROM by another. Note that this process will erase all your personal data stocked on the intern memory (contacts, calendar entries, SMS, MMS, emails, documents, photos, music, videos), but it will not erase any data stocked on the SD card. This is why you need to backup your personal data, using ActiveSync or, better, PIM backup and move your photos/music/videos to the storage SD card.
SPL = Secondary Program Loader... Read this to learn more or this for easier answer.
- How to check the SPL version I have? Answer: Enter the bootloader!
- How do I enter the bootloader? Answer: While your device is running, hold the Volume Down button and do a softreset.
- How do I exit the bootloader? Answer: Remove the battery cover and press the (red) Reset button using a sharp object, like a pen.
HSPL = HardSPL = Better and secured method to enable the flashing of cooked ROMs. Read this for more explanations
SSPL = SoftSPL = Older and less secured method to enable the flashing of cooked ROMs. Read this for more explanations
Goldcard = Advanced method to enable the flashing of stock ROMs from another country or region. It's not an easy method for newbie (and even for advanced users) and it's not free!
Part 2: Should I flash another ROM?
Discussion about the latest stock 1.66 ROM here in XDA.
Videos from Pocketnow.com about features of Windows Mobile 6.5.3
Videos from Phonescoop about features of Windows Mobile 6.5.3
Videos from Pocketnow.com about Landscape features of Manila
Videos from Pocketnow.com about New Document Tab of Manila
Part 3: What does HSPL enable?
Part 4: What should I consider before installing HSPL?