Micro Center has the mobo at $105 if you buy a Thuban with it, so the question is, 1055T, 1090T, or i7? I am not considering a quad core Phenom II because the 1055T is just $40 more than the 955 and $20 more than the 965. Is the 1090T BE's unlocked multi worth the extra $100? If there is no good AM3 mobo for $100-150, then I might as well go i7, in which case I would get the 860 from Micro Center.
As gaming is your main priority, as the above poster said, you need to decide on GPU first.
Both your selections are good. You at least want a 5850 (best bang for buck perfromance wise). This card can usually be overclocked to a stable lvl of almost equal performance to the 5870.
If you have the spare cash then the 5870 is the best choice (not as good a perfromance/cost ratio but then when you buy the best it never is) the performance from this card is excellent. I don't know its OC ability. There is actually a 2gig version of the card, though I doubt it is worth the extra cash.
The RAM you have linked above seems agreat buy. So I think if it were me, the link selling the RAM and card together is the one to go for.
As for CPU, I notice you mention the i7 as an option. If gaming is your main priority I actually recommend the i5 750 as the CPU to have as this CPU is highly rated for gamers and is a great OCer. I think Newegg sells it at $200.
For motherboard either go for low end or high depending on affordability and preference - I don't SLI or XFire as i always believe a powerful single card is better than 2 weaker cards and believe an XFire setup of powerful cards is unnecessary. If you decide not to go with XFire then the mobo you buy will be cheaper.
As for the monitor, as a gamer, I would suggest nothing less than 1920 x 1080 especially if using a card as powerful as the 5870. 24" Acer V243HBD is a good screen though likely more around $250, I could not see this model on Newegg though they had similar. It has a 2ms response time and is full HD. The way I see it, you will likely replace your GPU sooner than you will your monitor, so it is worth paying that bit extra for a good one.
You will want at least a 500gb HDD, with 7200RPM and ideally 16mb cache.
Possibly a non stock CPU cooler, I went with AC-FREEZER7-PRO-REV2 - Arctic Cooling Freezer 7 Pro v2 -which is very quiet, though not sure how well it copes with OCing.
5870 + 4gb RAM - $479.98 (from your link)
i5 750 - $200 (Newegg)
ARCTIC COOLING Freezer 7 Pro Rev.2 92mm Fluid Dynamic CPU Cooler - $39.98 (Newegg)(This new revision works with the new CPUs)
Acer H243Hbmid 24" 2ms - $219.99 (Newegg, down from $269)
MSI P55 CD53 - $90 (Newegg, no XFire or SLI) OR Asus P7P55D EVO - $132.99 (XFire)
500gb HDD - $55 (Approximately, Newegg will have plenty to choose)
Dual Layer DVD Drive - $30 (approximately, Newegg will have plenty to choose)
PSU Antec TruePower New TP-750 750W - $114.99 (Newegg $89.99 after rebate)
Total: $1204.98 without SLI or XFire
Total: $1247.93 with SLi or XFire capability
That's just a quick estimate of a build. You may find better deals on items. Note the mobo's were picked purely as an example price between one that can do XFire and one that can't - you will have to review mobos to find the one you want or perhaps someone will give a good recommendation.
Afriad I have not gone into AMD processor options and mobo because I tend to go Intel
yeah as posted above from astelian. its a good setup go rather for a bigger card then for 2 samler ones. drivers always slower to sli/crossfire and performence in meny games can go freaky depending on game/grapics. but a single grapics card whit multi gpu i got no problems whit.
Thanks for the help guys, especially asteldian! Picking between the 5850 and the 5870 depends only on how much I spend on the CPU/mobo. There is one thing though, I am not considering the i5 750 at this point because it is $180 at Microcenter, which offers the i7 860 and 930 for just $20 more. I am a guy who likes discounts, so I need either Microcenter's Thuban/mobo combo or their cheap i7 and a mobo from Newegg in order to fit the 5870 in my budget.
The i7 may be only a little more but it also then means you need a more expensive mobo (unless you go with i7 860). The reality is the i5 750 is probably still best value for money and the best choice as a gamer ESPECIALLY if you are OCing.
A deal is only a deal if you are getting something better for less, if you are paying for something you otherwise wouldn't want to buy, it is not really a deal.
i5 750 + P55 board probably will leave you enough for the 5870 if you wanted it