i used Windows 7 but same should apply for Windows XP. do remember that this is "beta" as stated, so if it still doesn't work might be a bug or a conflict with something installedon your pad
1)Downloaded the ra1n
2)Opened the ra1n
3)Connected iPad, iTunes autoopened but didn't close it, just left it open with the message it pops up
4)Pressed the button on ra1n
5)Held down the POWER + HOME button, as instructed on ra1n
6)Let go of the POWER button, kept held the HOME, as instructed on ra1n
7)Let go of the HOME button once the ra1n changed breaking or w/e the message was
8)Rebooted iPad
9)Turned on Wifi
10)Opened ra1n, let it load, click on Cydia, installed
11)Rebooted