To get the most up time, I'd run 2 workers with different pools per card. This way if one pool goes down, the other is still up.
How would that work? Using Phoenix miner, I would have for example:
./phoenix.py -u
http://worker_name:XXXX@useast.btcguild.com:8332/ -k poclbm DEVICE=0
and
<<edit>>
./phoenix.py -u
http://worker_name:XXXX@bitcoinpool.com:8332/ -k poclbm DEVICE=0
Is that right?