There is also "Nvidia System Tools" which allows you to control fan speed settings, if you prefer to stick with "Nvid". I use it with my 480 along with "Realtemp 3.60" to keep my temps under check.
Here's the link
NVIDIA DRIVERS 6.06
As for an upgrade, you should be able to pick up a 9800GT for around $100, not sure what ATI cards go for these days but they to should have something descent for around the same $ mark.
cheers