I activated a copy of XP Home on my spare (dual boot)computer a few weeks ago but now may need to take it off and reinstall it but I am not sure if it will run or whether I have to phone MS?

How much new hardware can I install? I need to install a NIC and graphics card in my spare dual boot ME/XP machine (soon to be tri boot with W2K Server) and I also want to upgrade my hard disk. Can I do this without losing my XP activation?