I just upgraded the HD in my laptop using a PC drive. Macs use the same memory and other parts as PCs too. The mother board is from Apple and the processors are from Motorola and IBM depending on if it is a G4 or G5 chip.
I use a laptop only these days. Really you can't do a whole lot of upgrading to a laptop no matter who it is from and Apple does make nice laptops.
This is the newer version of mine, still looks the same.
http://www.apple.com/powerbook/index17.html