Yes it will. Not by a whole lot, and you'll still get playable framerates in all games, BUT you'll often drop to 20 or lower in CPU-heavy scenes. Your maximum framerate will also be capped at about 75% of what the card can do with a powerful (read: Sandy Bridge) processor.
Omgitzfatal is right - get the card now, and upgrade to an LGA 1155 platform when you get the funds. That's my plan. Also convincing the wife is a vital step.