Mac!
Trust me, i was in the same scenario last year until i checked out a Macbook. It made the difference.
There were a few parameters that mattered for me:-
1. Resolution and colour since im into Photography.
2. Digital Music handling capabilities since im into music.
3. Portability.
4. Speed and Robustness.
And the Macbook Pro had it all. For your case you might not need a macbook pro though, check out the simpler ones.
AND if you are thinking you might not be able to run your old windows applications or software, dont worry you can still do them on a Mac. (Intel based Mac with Boot Camp software).
