I have a (Time) AMD XP1700 pc, with home edition and 512MB of DDR RAM.
It has a GeForce2 MX400 64MB DDR graphics card.
It's a couple of years old.

The cpu is actually 1500MHz, and I know the motherboard is 4xAGP.
(512MB is max installable memory, PC2100 I think)

I was thinking of changing the cpu to a faster one (I've been told it
will take upto around 2.2GHz depending upon the make of motherboard).

Will this force me to re-install XP? Or will windows just boot as
normal?
Will I have to fiddle with the registry/bios?
XP came pre-installed so I don't have a cd.

Is a fan/heatsink upgrade necessary for the new CPU too?

If I do have to re-install XP, will this format my hard disk? Could I
get around this by adding another (faster!) disk and doing the new
install onto that?

Also, if I upgrade my graphics card, do I have to get one that's 4xAGP
or will an 8xAGP card be able to use the 4xAGP? (Presumably at 1/2
data rate?)

Sorry for all the questions, but it's getting a bit slow by todays
standards and it could do with a few upgrades!

Thanks.