The choice is between two HIS cards: HD4650 (512 MB DDR2) and HD4670 (512 MB GDDR3). Neither requires external power (plus) and the spread is $10 (the more expensive card is $79.95 before tax/shipping:http://microcenter.com/single_product_results.phtml?product_id=0298239). Both cards are realistically dual-slot (even if the HD4650 is technically a single-slot design), so they even take up the same amount of space. 1024 MB is not an option (4 GB address-line limit of the nForce 630i chipset; I can't even upgrade to 4 GB of RAM), despite running 64-bit operating systems (Windows 7 currently) exclusively. (Chipset limitation, not OS limitation.) While tthe two GPUs are similar, is GDDR3 worth it?