Both are good choices. I too was torn between Infinity Betas and Polk Monitors. I decided to get the Betas but since circuit city was out of stock i got the Polks (monitor 30s) instead.
I think the general consensus is that the Betas are slightly better, but either is a great choice :) If you read some of my other threads you'll see that i have been stressing out on the Polk vs Infinity topic and which i should have gotten :P
EDIT: hey i didn't realize it was you that had posted this haha. Talk to me on AIM if you want to discuss it :)