i7, good cheap mobo. SLI/xfire: http://www.newegg.com/Product/Product.aspx?Item=N82E16813130227
If you get a micro center deal i7 FTW. Even if you get a Asus Gigabyte mobo, $100-$200 difference for triple channel and sli/xfire, your still better off goind i7.
I was gonna build my son a i5, but now I'll just get him i7 with those prices.