Try turning off all your security and test just to be sure. sometimes the type of security you're running can cause it to act wonky. Then if that works of course play around with those settings and see if you can flush it out. Also before doing any of that perhaps try running a long ethernet to the machine just to be sure it's the wireless only.

I've always had issues with my PS3 wireless being slow as dirt though. My 360 downloads content about 4x as fast.

I've got about 15 or so good friends with 360s which we play online together a lot. About half of those guys (and gal) have PS3s and I can tell you now I think all but two of us have sent our 360 in for red ring. I also had a 360 I bought for my old office that I had to send in TWICE. Not a single one has had to send in their PS3.

That's the irony, though. 360 is gangbusters for it's online play and game selection, but the PS3 has been rock solid and a great media machine. It's a shame really. I pretty much only buy exclusives for the PS3. Everything else I get on 360.