Other than the case being beat up, it looks OK inside. I can't vouch for the condition, but the seller has a nearly 100% feedback score over nearly 31,000 transactions. That is a plus in his favor for sure.
As far as the system itself, it is old, outdated, but still capable of providing some good service. I have that same exact model in the T3500 variety with a Xeon W3670 6C/12T processor and 24 GB RAM. Your selection has a 4C/4T processor, business type gfx card, and only 3GB system RAM.
It says that it has a Vista COD. Which would be fine if it had a recovery partition to...