joining a mining pool that pay per share and do CPU mining is an option.
yeah... that wouldnt be good as far as ive read
a (decent) GPU outperforms a (decent) CPU by a factor over 100
the CPU would be at 100% (or close to) load too, so the thing would be useless for everything else also
make the CPU miner run at idle priority, so its only using spare cycles to do mining then it won't affect anything,
also if you look up the OP's setup, seem like its one of those mini all in one design with no ability to use a discrete GPU, otherwise I would have suggested that.