Yes the 4670 is the king of the mid power video cards. Next step up would be the 4830, which would need the power adapter, which uses 110w. The 4670 uses 70w. The 4650 only uses 55w but at a noticable performance loss.
SAPPHIRE Radeon HD 4670 512MB 128-bit GDDR4 $79, $69 after MIB.http://www.newegg.com/Product/Product.aspx?Item=N82E16814102818
Most 4670's are around $80 but this is the only one with GDDR4 and its by Sapphire, a reputable brand. All good reviews too.