You can easily swap components?
I just upgraded my fathers PowerMac from 512Mb 667 DDR2 SDRAM to 4Gb ... I didn't see any problem? As Apple says
"Isn't it nice when things just ... work?"
I've worked with Photographers that have invested thousands into PC's and decided a PowerMac is better. I see that movies in Hollywood are always being made using a Mac, and when I watch an international rugby match I see the coaches using PowerBooks in the stand?
Any reason? ... Nothing against PC's but I prefer a Mac, people love the iPod / iPhone / iMac ... etc so we can't all be wrong