Jeff:
The HP q9400 video is apparently a discrete card, rather than on the motherboard. The q9400 processor is faster than the q8200 in the Gateway. Look at my links farther down. The Gateway has more ram. Try to configure the HP as close as possible to the Gateway.
The Gateway has “up to” 1 gig video. The video would appear to be built into the motherboard, not a discrete card, so some of the 8 gigs system ram is going to be used by the video card. Price 780 plus tax at Best Buy. Out the door probably 840, depending on Fla tax rate.
The Dell Core i-7 920 has 256 mb video on a discrete card, not on the motherboard. Price 899, probably no tax. You can upgrade to 6 gigs ram for 100, total 999. Is shipping included?
Retail processor prices at Newegg:
8200: 165
9400: 230
9550: 275
i-7 920: 280
Re processor comparisons, look at the link below for a comparison of many quads, including the 8200, 9400, 9550, and the i-7 920. The various charts, tables, and pages at the link below discuss overall performance, gaming performance, image processing, media encoding/editing, and “bang for the buck” when all other variables like RAM, video card, etc are held as constant as possible.
http://www.techreport.com/articles.x/16570
I won’t post the graphs here, but the “average performance” graph shows the i-7 is about 18% faster than the 9550, 25% faster than the 9400, and 42% faster than the 8200.
In the media encoding test, the q8200 took 119 seconds, the q9400 took 105 seconds, the q9550 took 98 seconds, and the i-920 took 74 seconds.
The Dell i-7 is about $59 more than the Gateway and you have to decide if you want to pay $59 for that level of increased performance.
Re vendor: you are just going to have to swallow hard and hope. Given that you apparently are limiting yourself to Best Buy, Comp USA, and Dell, I would choose Dell first and Comp USA last, but to each his own.
Make sure all are configured to do what you particularly want to do with the machine. I have no idea how sensitive you are to, say, a $200 price difference. Personally, I would be much more concerned with the proper components and the vendor, rather than the $200.
Regardless of vendor, I would get an i-7. The price differential is minimal and it has the new socket. The other traditional quads use a 775 pin socket which Intel is phasing out. I don't know if you might upgrade the processor after 3 years or so, but if you don't get an i-7 motherboard now, you will be limited to the older quad processors in the future--or buy a new motherboard as well at that time.
I assume you could not price a Nehalem machine at Best Buy? Not surprising I guess as Dell has quicker access to Intel's new lines than the typical retailer.
I would seriously consider a second drive of some kind for backup purposes if you don’t already have that covered.