The best builds I've used are NexusHD2 1.8
(if you want completely stock Android) and MDJ Froyo HD 4.6
(if you like the HTC Sense look). You will need to flash your HD2 using ActiveSync with a new '.50' radio. They can be found here
(126.96.36.199 is the one I'm using). Without the new radio you'll be unable to boot.
I'm currently running MDJ Froyo HD 4.6 and it's quick and stable with pretty good battery life. I experience trouble with 'robot voice' when calling on NexusHD2, however everything else works just fine. Once you get a bit more confident you can have a play with custom kernels and whatever else.
To install one of these builds follow the link and download the package, then extract everything. I take the MicroSD out of my phone and use a card reader plugged into my PC to format the MicroSD FAT32. Quick format works fine for me. Then I copy the files into a folder called 'Android' (do not use all capitals) in the root of the SD card. Then boot into Windows, use file explorer to find your 'Android' folder and run CLRCAD.exe (nothing will happen - that's fine). Then run HARET.exe, click 'yes' when told about an unknown publisher, and it will proceed to boot you into Android.
First boot may take up to 10 minutes, as the device creates a virtual 'phone memory' for your apps and sets up the kernel. Once it's booted and at the lock screen, leave it for fifteen minutes. After fifteen minutes, unlock and power off your phone completely. Rinse and repeat the booting process, and your Android should be working perfectly.
I'll keep an eye on your thread in case you have other questions. Make sure you flash that radio first, or you'll be in all kinds of trouble.