This is going to cause you all sorts of problems... XP is a 10 year old OS, it is obsolete. You should be going forwards instead of backwards.
Windows Vista is actually 3x as stable and 5x as secure as XP straight out of the box. Vista with SP2 runs as fast as, IF not QUICKER than XP SP3. Benchmarks don't lie, and neither does any of the software that is going to be released in the next 5 years, which is going to be hard-coded to only run on Vista or higher.
The issue is that the way programs interact with the Kernel has changed drastically from XP to Vista, and slightly with Windows Seven. Compatibility may not be an issue yet, but it will be.
Think about it.
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