Try a different miner.
50Miner has a nice, newbie friendly UI and I can confirm that it works with 5450s pooling to BTCGuild.
I installed 50Miner and it appears to be working. At around 14 MHashes/s, how long should I expect to find a "share"?
Also, are there any settings I should know of?
Also, also, it crashes when I have it set to cgminer so I have it set to poclbm and it runs fine (i think).