i was actually looking to buy this. someone is selling it for $550 and i was wondering if it was worth it. i'm planning on getting another radeonHD 5770 and crossfiring the two.
Google microstutter and see if that will bother you re the hd5770s crossfired.
A refurb I5-2310 like this one is less than $400 at acution. Dell Inspiron 620 Intel Core i5-2310 2.9Ghz 6GB 1TB http://www.ubid.com/Dell_Inspiron_620_Intel_Core_i5-2310_2.9Ghz_6GB_1TB/a603597686.html
I'd say it is comparable if you added a $100 HD6770. So $550 is not totally out of line for the x6 system which has quality parts.
If you know and trust the seller and know the system has not been overclocked with high voltage then $550 is OK. If you do not know the seller then this is a pretty high price. Comparable x6 1100T systems on ebay are asking $400-$450 with less memory, worse PSU and no video.