I didn't like the Aero scheme in Windows 7 at first. (It is new with Win7). But it kind of grew on me. I am a keyboard traverser. That means I like to traverse with the keyboard whenever I can, and only use the mouse if I have to. I use "Alt-tab" to switch between different windows very often. When I changed the aero scheme to "best performance".... the scheme was like XP... one annoying problem: Alt-Tab doesn't work intermittently. You can press Alt-tab all you want, the icon bar for selecting different windows would pop up for a fraction of a second and go away. You can alt-tab alt-tab alt-tab until the cows come home and it doesn't change your active window. I switched back to the default in Win-7 ("best appearance" I think). Everything works fine without problem.
It takes a little to get used to at first with the new Aero scheme. Like mouse-over the task bar application icon, it will display different instances of that app (Word, Excel, etc.) that you are working on, and let you moust-over to select the instance you want to get back to. It is nice.
So... I would say that if your CPU is fast enough, and you have plenty of memory, go with the default Aero scheme. The convenience, plus the non-buggyness, may grow on you too.
And with Aero, now Windows-Tab will give you a 3-D rolodex to select between different apps. It looks nice (is it Apple-like?)... though I don't use it often. (Was this Win-tab new with Vista? Can't rememeber)