Your temps are fine.
GPUs are designed to take a lot of heat, yours specifying a maximum temp of 105c.
Before I replaced my stock coolers, my pair of 4850s would idle around 65c and routinely hit 95c+ with no issues.
If you really want to lower the temps a little, upgrade your cases cooling and/or your GPUs cooler.
If you do not want to spend any $ upgrading, do not worry to much about it.
Your GPU temps are still well within specs.