I'm surprised to read that... on Thom? Plain yellow Thom?
The specs you have are all way better than the computer I'm on and i don't have any trouble with Thom. Something must be wrong.
One thing to check... go to Tools>Options>Global and check "Limit real-time subdivisions"
That stops you from going past 4x4 subdivisions with the Page Up key in shaded mode.
Let me know if that changes anything.
Edit... I'm looking at me video card specs I have 2GB rather than your 1GB. maybe that would be why?
experiment... try setting your monitor resolution to something small like 1024x768, run A:M, load a model and see if it is still slow.