OK, but just an opinion. I believe in PC's. They are more durable, upgradable, and cheaper. The only problem with a PC is the space. But part of that is organization. PC's can be plenty strong.
I no your pain, I upgraded in three years time from the old one. What a difference. If you are moving up 5 or 6 years, you'd better get a seat belt on because that long is like night and day. And make sure you get plenty of ram. I actually upgraded imediately when I first got mine from 1024 MB to 2048 MB.
Fast is all I can say.
PS I was on a 128 upgraded to a 256.