I would probably help to try and bump up the hashrate, but these days it's pretty much pointless without ASICs.
My new video card would have been useful back during the first few months but now that Scrypt ASICs exist.. eh. I just don't see the point in mining anymore.
If you can afford the electricity during the high difficulty periods, you might actually make a difference with a GPU.
What I've noticed is that a single ASIC rig/instance of sgminer/cgminer will sometimes go for a very *long* time before finding a block, and just having a video card running along with some big asics gives you a chance that the sgminer/cgminer running your GPU will have a different random number generator seed than the asic (or even a much better cryptographic random number generator period), and you might find a block. This is only my intuition, however, I have no real good data to back it up.
It's not profitable, but neither is running an ASIC system unless you profit-switch for 10 blocks with twice the long-term average hash rate.