Money spent on older mb's might not be cost effective but
GIGABYTE GA-G41MT-USB3 LGA 775 $50 [ after rebate ]http://www.newegg.com/Product/Product.aspx?Item=N82E16813128489
Amazingly this has USB3 so its been made fairly recently and is not just old stock . The G41 chipset is decent enough too , and you may find the onboard graphics useful [ like when the 8800gt blow up ! ] . Dont be put off by it being m-ATX unless you have 5 expansion cards you want to use .
Patriot Signature 8GB (2 x 4GB) $35 [after rebate ]http://www.newegg.com/Product/Product.aspx?Item=N82E16820220570
Is faster and lower voltage than the mb would have originally supported so it wont run at its top speed without some overclocking . But when you do build your next system you should be able to reuse it
Without knowing what kind of graphics card you might one day use a PSU is only a guess . For now a good quality 450 -500 watt unit should do and let you upgrade graphics to a very decent card later on . 650 watt would be overkill but could pay off eventually .
As for cases . Check out Newegg . IMO Antec, silverstone, coolermaster make decent products for a range of uses