What do you mean??? You mean MTP, mass storage??? I never tried XP with this phone but theoretically it should works. Try check for the latest samsung drivers maybe??
I tried Vista, 7, 8 and 8.1 with working adb, MTP and mass storage. Download mode will not work for Windows 8.1 which is the only issue that I've faced, all other OS are working good.
Go to the galaxy s themes and apps section and find the thread with the Samsung drivers
Ok with W7 works, now install driver for XP but is very strange that with all roms i tried works and now not... Maybe XP is BECOMING EXTINCT
This ROM seems the best for our phone abaut responsives app and for games but JB is more smooth scrolling home
Download and install Devon-Team TWRP or CWM recovery from this forum, here the link: http://forum.xda-developers.com/showthread.php?t=2463347
Be sure also that your device us not affected by emmc bug, in this case use the special recovery for emmc bricked devices (available for download in the same tread).
I've just installed CM9 yesterday using TWRP and all work fine.
Hi, you can flash the PHONE/MODEM firmware independently whenever you want, it's written here in the xda wiki page for our device, in the section on ROM parts: http://forum.xda-developers.com/wiki/Samsung_Galaxy_S_Plus/GT-I9001#ROM_parts
As usual, after flashing anything clear caches.