The only thing I'd be worried about there is the PSU, because often cheaper ones are rated a bit too high. Still, that sounds like it should work.
No need for PSU concerns here. I bought a new power supply for my miner (a single 5870) only to discover that under full load and overclocked my entire computer consumes a paltry 207w of power.
A 550w PSU will be more than enough.