Of the two I would go with the dell err I mean I went with the dell
For the dell I would drop the memory down to 256 megs and save yourself $225 Then buy some memory from crucial/kingston or somebody and save yourself money over buying it direct from dell (it takes one screwdriver and about 5 miniutes to install the memory) I think when I was looking it was about $100 - $125 or so get get an additional 512 meg of memory (so for the price of your upgrade you could almost toss what came with the dell and buy a gig of memory to install (2 X 512) and toss/ebay the 256 meg chip.
Like I said before I get about 4 hours of battery life from my 8600 with the ATI 9600 card in it just doing normal stuff with the standard battery. If you get it I would also reccomend getting the media bay battery so you can get up to 7 hours of life if you need it. You would have to remove the CD-ROM to put this in but if you rip your games to the hard drive and emulate the CD's you will not need the CD-ROM that much anyway.
If you decide to go with the dell you might want to think about the faster speed hard drive. If can greatly improve your access speed for games if you are worried about they type of thing. It will kill a bit more battery but it might be worth it if you play lots of games.
Widescreen - How well do the games you want to play support the widescreen like you would have on the dell ? I am not much for most gaming right now but NFSU looked ok playing for me. When you are running in a resolution that is not the native for the LCD things can look a little bad.
The 8600 is Starting at 6.9lbs according to the dell site.
