I really don't think they could/would be that incompatible. I've certainly never had issues dual booting XP and 7.

I'm tipping something more like the SSD went out. But that probably wouldn't explain the errors you saw in your XP installation.

FWIW : I do rate Windows 7 over XP. I had been on XP on my work machine until January. New machine and Windows 7 came with it. Of course it's newer hardware, SSD etc but still I think 7 contributes significantly.