I've been using ps3 media server for a few months now and how excellent it is too. However I have a wireless network and was getting a few stutterings here and there, which required frequent trips upstairs to check what was going on and much tinkering. Anyway i decided to bite the bullet and upgrade my network to wireless n and wire up the ps3 to the router as ps3 only has wireless g capability. Last night I was streaming a wmv hd 1080p file flawlessly I could see it reachin 80Mbits without issue. Transcoding was stuttering but I think this was down to the cpu being hammered (I've got AMD dual core 2.9GHz on windows 7 RC) but not confirmed. It's cost me £60 for the new router and £18 for a new wifi card.
So anybody else considering upgrading it is well worth it.