Go for the Dell XPS 17 range they are better value for money than the HP model you are looking at
HP DV7 - $849
CPU - 2.3GHz AMD quad-core A6-3400M accelerated processor (4MB L2 Cache)
Screen - 17.3" 1600x900 resolution
RAM - 8GB DDR3 SDRAM
Hard Drive - 750GB 5400RPM
Optical Drive - Blu-ray player/DVD burner
Graphics - Radeon HD 6520 discrete-class graphics, up to 4085MB memory (on-board)
Dell XPS 17 - $899
CPU - i5-2430M processor 2.40 GHz with Turbo Boost 2.0 up to 3.00 GHz
Screen -17.3" 1600x900 resolution
RAM - 4GB DDR3 SDRAM
Hard Drive - 500GB 7200RPM
Optical Drive - DVD Player/Burner
Graphics - NVIDIA GeForce GT 550M 1GB (dedicated)
CPU - The dell wins this by a long way.
Screen - These are the same resolution and only build quality will be the difference, I might side with HP on this one.
RAM - You do get more in the HP, but RAM is cheap enough and you can upgrade easily.
Hard Drive - I would always try to go for a 7200 with slightly less storage, over a slower 5400 drive with more storage, the dell comes with 2 hard drive slots so you can always add another drive later if you need the space, or add a SSD as the primary drive for increased performance.
Optical - I wouldn't bother paying for a Bluray drive on a laptop that does not come with a full HD screen as it is pointless.
Graphics - This is not even a contest, the 550M is a dedicated graphics card with it's own memory and wipes the floor with the one on the HP which is built into the AMD CPU and uses up system RAM.
As you can see for just $50 more you would end up with a lot faster and better CPU, a Faster Hard drive and a lot better graphics. Trust me you would notice the difference between these two laptops.
I would without a doubt go for the Dell XPS 17 over the HP DV7, the extra cost is worth it in the long term.
I have one of the XPS 17 laptops and can not fault the performance and can say that it runs a lot better than other laptops similar to the one you have been looking at.
You can check the difference in performance of individual parts such as the CPU and Graphics at netbookcheck.net
This will show you just how much better the Dell system is.