Linux Mint is based on ubuntu so you could try another distro that isn't ...
Fedora - Mandriva - Mepis - SuSe etc ...
Try running it from the live cd before you install it as well.
I have found the they run better on intel hardware out of the box and AMD systems need tweaking.
This experience comes from running linux over the last 9 years ...
Also, I don't install the OS on the same hdd ... I find it better to add a 2nd hdd and run it off that.
Good luck
