All excellent choices except for the mobo and maybe the GPU imo.
No reason to get a mobo with an nvidia chipset like the 780i (since they're not as stable as the current intel chipsets) unless you're determined to go SLI, which most people don't recommend since the performance difference rarely justifies the cost.
New GPU family coming out next month - so you can then either get the latest and greatest or at least pay less for a 9800 series when the price drops. If you have to build now, consider a card like the 8800gt 512MB (170$) which will still max out most games on the market currently but costs less, so you won't feel so bad about upgrading a year from now. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
As I post all the time, I would buy an 8800GTS 512 g92 card for around $200 before I would spend a hundred more on a card that is only about 2% faster. The 9800 is simply a rebranded 8800GTS with a little faster memory, that doesn't really mean much. An 8800GTS will easily overclock to speeds of the 9800 and faster.
The 9800 will do triple SLI though and the 8800 won't. (for what that is worth)
I want to spend money as less as possible and still get a pretty decent gaming rig (basically, I'm capped at 1000$ now ). What do you guys think of this? Oh, and I chose a SLI motherboard because I'm considering SLI'ing the video card in the near future. Also, can anyone tell me what are the differences between the MSI P7N SLI Platinum motherboard and the ASUS P5N-D motherboard? They are at same price so I don't know which one to choose
Get a WD6400AAKS or WD7500AAKS from newegg instead of that ancient WD5000AAKS without PMR. Major speed difference. Check my config, this one is from personal experience, not just reviews.
The rest sounds nice.
The MSI seems to have better features than the P5N-D (eSATA, for example, or the third PCI-E x16 slot). It also seems to make more newegg reviewers happy (62% love it, 3% hate it - both numbers are better than for P5N-D). This is totally unscientific, I know, but I'd get the MSI anyway if the price is the same