Well, if I had the choice I would take the Vaio, more or less becuase I like the Nvidia card in it better. Thier doesn't seem to be much major difference other than cosmetic. (And again vid card) I personally also like that the Vaio has bluetooth but I don't know if you will be using it much at all. I also like how the Vaio is lighter. I hate heavy laptops.
But for your usage it seems that either one will do very well, the i7 on both of them will be a multitasking dream. I've run many intensive programs with my i7 and haven't had any hiccups or slow downs. Of course with the 6GB model you can be running more programs at once but in 99% of cases you won't be exceeding 4GB, and even if you do it will extend to virtual memory. Looks like both of them have a BluRay in them so you don't worry about your disk formats if your playing lots of movies. However the Dell does have a larger screen, so you might like that more with your movies.
It looks like both of these would be able to play Call of Duty and then some. You should be good in this field for a couple of years.
You should be good to go on the music storage unless you find a way to occupy 500GB, I was never able to do it but then again I clean my system out quite frequently.
Again if I had the choice I would take the Vaio, but for budget wise, thier almost the same in terms of capability and the Dell is a little more than $100 cheeper. (or $250 if your talking about the 6GB Vaio)
Hope this helps!
Edited by xXAlphaXx, 14 April 2010 - 06:46 AM.