If i want to reformat my HD, and i want to re-install my Windows XP, I was wondering if it will let me install my copy of Windows again.
(used once already). I tried doing this with Microsoft Works Suite, but i was told it could be activated once. Just wondering before i have to go and buy another Win XP.

With a full version or up-grade CD there should be no problem.
It should work on-line, or you may need to make one phone call.
Here is a Microsoft page:

Frequently asked questions about Microsoft Product Activation

Thanks..!! Ill look over the FAQ page.

on a side note, after about 20 times, your activation key will no longer be valid, yes it will work, but went you try to activate, it will say its overused (more professionally though), but you call a ms rep and theyll take care