Can't really answer the question unless you give us an idea of what tasks you rely on your computer to perform? What kind of apps do you run?
If you're an average user (word processor, finances, email, web browsing, some music and pictures) then the cheaper Celeron/AMD chip based systems are perfect. Hell, for $350 you could easily build a nice system (not including monitor) or for $500 buy something from Dell or Gateway with support. Actually I recommend you seek out a local computer shop that sell prebuilt machines - usually they offer better hardware and only install the software you need.
All is not well in the MAC world
Unhappy MAC users. Probably a small group but just shows that MAC is not the perfect bug free environment its always touted to be either. Still, MAC users are pretty fanatical
- and their OS-X operating system is sweet. I just can't swallow the cost of their hardware.
Good luck.