i would wait for Ivy bridge and a z77 mobo. things like x63 multiplier, lower power consumption due to a die shrink means lower TDP so cooling needs will be less, native USB 3.0 and native 1600MHz RAM support plus im sure they have snuck in some extra features over p67/z68 platform. I am sure it will be worth the wait and you wont regret it. in the end you will end up paying from similar or less prices to maybe 10% more max depending where you shop and what deals you find over a new sandy bridge platform. my estimate for an ivy I53570K/ mid range z77 and 8GB ram would be around the $450 so is $250 enough for your gpu? can i save more between now and april? these sort of question are what i would be asking myself
also we are starting to see alot of used sandy bridge cpus emerging on the second hand market as well as entire rigs as people have started selling off in preperation for IB IMO is the reason why..