If I just upgrade the same xp machine to win7, will that fix it?
XP to 7 requires a clean install, it does not upgrade in place preserving your applications, you have to reinstall everything.
That said, I've not heard of anyone seeing the slowness on WIN7 and have heard several people who switched to new WIN7 machine and it fixed the slowness. But that does not differentiate between the new machine and WIN7. I have not specifically heard of people upgrading their old machine to WIN7 and whether that fixes the problem. Someone has said "WIN7 may not fix the problem" but I'm not sure what they were basing that on.
I'm getting a new WIN7 laptop friday and separately a copy of WIN7 Pro. I'm hoping to be able to compare 3 things:
1) Old laptop with XP
2) Old laptop with WIN7
3) New laptop with WIN7