Yeah - another vote for VLC. Do you have the latest version of quicktime installed. I found that when I first got Quicktime 7 I couldn't smoothly play back Hi-Def H.264 files, but the latest version fixed that for me.
Logitech MX518 Mouse
WD 200GB External Hard Drive
Some Cheapy Altec Lansing 5.1 Speakers (251's I think)
Sennheiser HD555's, with a PA2V2 Amp (generally these get used more with my ipod than my laptop)
Big old Targus...
With my HD 555's the sound was definately improved and got better. Its very discernable, especially the increased bass. However, I just burned mine in by listening to them, you don't need to pump white noise or somesuch through...