Hey fellas.
I was mining yesterday with guiminer at slush's pool and I got the average 80mhash/s. My GPU was at ~85 ºC at 100% fan speed (1800 rpm). My fan is an Evercool Buffalo and my GPU is not overclocked: 750mhz gpu clock and 900mhz memory clock. I got like 16 shares in 15~25 minutes, is it good?
Is it worth mining in these conditions?
I would keep mining, especially with a pool.
As well, there are other tips and tricks that can help bump up your MH/s rather easily. Poke your head around some of the other forum threads and see if you can't learn small things that will bring up your hashrate some.