Help! CudaMiner running at fraction of speed of GUIMiner

[swtennisballs]

I connected CudaMiner and GUIMiner both to slush's pool, one at a time, to see if there could be a difference. I noticed I got >25 MHash on GUI but only about 50 KHash on Cuda. I use a GT640 running all the recommended drivers.

My .bat for CudaMiner is:
cudaminer.exe -o http://api.bitcoin.cz:8332 -O [MyLogin].[Worker]:[Password]

I wanted to switch to Cuda as I heard it was better and to possibly mine other types of coins.

Any help would be great.