Dell XPS 15 vs 21.5" iMac

Hi everyone,

I've long been a reader of this forum, lots of great advice on here. I am planning to purchase a new system for school by the end of august. Below I have listed the components on the two machines

Dell XPS 15 1077.95$ + tax
Intel i7-2630QM @ 2.00 ghz with TurboBoost up to 2.9 ghz (4 Cores / 8 Threads)
Nvidia GT 540M 2GB GDDR3
8GB DDR3
750GB HDD (7200 rpm)
1080P Display
8x CD/DVD Drive

Apple iMac 21.5" 1149$ + tax
Intel i5-2400s @ 2.50 ghz with TurboBoost up to 3.3 ghz (4 Cores/ 4 Threads)
ATI Radeon 6750m 512mb GDDR5
500GB HDD (7200 rpm?)
1080P Display
8x CD/DVD Drive


Mobility isn't a huge concern to me, I presently have a laptop I could use should I need to use one.

I'll be using this machine to do:

Presentations / Papers (General school work)
Light Photoshop work
Entertainment (maybe once an adapter comes out I could use the iMac as a display for my xbox360?)
Playing Starcraft 2 / Portal 2 (I'm really not that big of a gamer, but I'd like to play the games in high quality)



I'd prefer to avoid the fan boy discussions etc. and just come to a conclusion. I have built computers through highschool but that was 5-7 years ago, and now with all the new technology that has come out since then it's rather overwhelming to get back into it. I'm particularly confused about GDDR3 vs GDDR5. On Netbookcheck.net both cards scored -/+ 5% of one another's benchmarks, as well I'm a little lost about the i7/i5.

I would like to keep this computer for the next 3-5 years, once I finish university in the next two I can build my own full desktop once again.