I live in London, so I realise it's not profitable to mine - but I want to try it anyway...

My desktop machine happens to have two Nvidia cards. Model GT 430 , nothing special.

Can I mine anything at all with this machine, and in that case, what mining software do you recommend?

I tried GPUminer but I was only able to mine with one of the cards - don't know why.

I also tried Bitminter's client. It mined a bit faster than GPU miner, but the cards got a bit hot. Had to take out a PCI card that obstructed the airflow.

What is a "Cuda miner" and is this what I should go for, since it's dedicated to Nvidia? If so, which is the best and where do I get it?

I could really do with some advice! Hope somebody can point me in the right direction?