Mt dual Xeon Quadra graphics beast with SCSI 320 Raid 0 drives was needing replacing.
It had AGP graphics haha, it was about 4 years ago now and I think PCI Express had been out for one or two years so it was getting on a bit. I had dual 17" LCD's too.
But I never used it for much, I built it cause I was in IT at the time and it was a bit of a dream machine with the parts heavily discounted, anyway my sister had a Mac and my brother in law kept going on about them. So I test drove the beta Vista and whilst it was ok, I was worried with all the horror story's.
So I thought Mac, I also thought Mac Pro, then came to my senses, haha, realising I would just be willy waving as I would NEVER use it's power, and then I saw the MacBook Pro and fell in love

So I got one, and got use to OSX and haven't looked back, Macs have got stronger and stronger, I have Windows 7 installed as well for some games and the only drivers you need to worry about are the graphics ones and that's if you want.
So far I had the old style MB Pro but I utterly HATED the keyboard.
Got the first gen unibody to resolve that.
Got last years Corei7 cause of the performance bump for games.
Now plan to get this years mode, because I didn't expect a 50 to 100% performance boost over last years model

and ATI graphics

plus I have some shares that hopefully will be awarding me some cash.
Anyway, OSX is bomb proof nearly, and Macs are VERY well built. It's the swiss watch of laptops.
Now I WAS thinking of an Alienware Aurora, not sure why? I think for games, but the MB Pro is just far too sexy and lush not to have, plus I can take it anywhere I please and play Portal 2 or Windows games. Macs just rule really... it's also pretty ironic that my laptop's of choice are more powerful now then the desktop they have replaced!