Potential PC problem

So here's the thing, I got a nice hefty tax rebate of £1871.95 so I decided to upgrade my PC (among other things) to this: Battlefield War Rush Intel Core i5 2500K 3.30GHz @ 4.40GHz DDR3 Limited Edition Quad Core System []

I have upgraded the GPU (to the 6770) and the RAM to 8gb and now I get to the potential problem, I have 2 HDD's in my current PC, I want to take one of them out and put it into my new PC, only they both have XP installed on them, will they be compatible with my new PC? Is there anyway to remove the protected windows files without having to delete everything else on the HDD? Should I remove the GPU driver? If this can be put into my new PC then I would also upgrade the HDD to an SSD.

Yes, yes, doesn't matter.

As long as your old hard drives are S-ATA, or your new PC has an IDE connection slot. Chances of at least one of those being the case are extremely high.
Windows files are only protected from deletion when you're running the OS that uses those exact files. To a different Windows installation, these are just normal files like any other bunch of files.

Thanks for the info, just thought of another potential problem, the HDD is partitioned, will it still be partitioned when I stick it in the new PC?

Yes. You can easily clear the partitions after copying what you want to keep, and then repartition with one large chunk instead of several small.