I'm utilitarian, so right now I use a Mac, because it's the best computer for my needs.
As for being bogged down, I have that problem myself.
I use GIMP instead, because I have no money for fancy schmancy stuff (plus the damn serial cracker didn't work...)
I only have 512MB so far, and running certain apps, often java based, tend to bog it down pretty good.
Also, I think it's pretty weird how it's even possible to create a simple gallery program that's half a gigabyte big (iPhoto) when Google picasa is 1% the size and a much better program...
So their apps aren't the most optimized I've ever seen.
Don't run other heavy programs at the same time, especially java, get some more memory, use intel-compiled programs rather than universals if you can.