I installed winxp pro on my other comp and after the computer starts up, it says 30 days to activate, and when i click on it to activate i put the Product Key and it says : "According to our records the number of times you can activate this product key has exceeded."
What do i do? Dont tell me i paid 200 bucks to only be able to activate once.                  :-/  :-/   :-/you may have to phone m$oft on this one..and argue with them.. more info>http://aumha.org/win5/a/wpa.htm and more>http://aumha.org/win5/a/wpa.htm   or this tip>>>>>>>>If you are doing a repair reinstall of XP on the same HARDWARE, you can back up the activation status and then restore it after you run the repair install of the OS. To save the activation status, back up the wpa.dbl file from the %systemroot%\system32 folder to a floppy disk.

After the repair install of the OS is complete, start in Minimal Safe mode. Open the \%systemroot%\system32 folder.  Rename wpa.dbl to wpa.noact. Copy the backed up wpa.dbl file to the system32 folder. Reboot your system.

This isn't a hack to avoid activating installations and will work only on the same hardware for an XP installation that you've already activated.
You should be able to install Windows XP on two machines. The upgrade, that is.As an aside, you do KNOW you can also activate XP by phone, fax, snail mail, pidgeon post (PROBABLY)...And if all else fails, TAKE your local Microsoft PR agent hostage.