Hi, if you have been using your GPU it will start to heat up, it's those pesky laws of physics again.
You use your GPU a fair bit just by having windows Aero enabled so there isn't an easy way to avoid this.
To monitor your GPU temperatures I would recommend using Nvidia's own software available from NVIDIA DRIVERS 5.05.54.00
but other third party solutions may be easier to use.
As long as your GPU doesn't break it's critical temperature (usually 100ºC) you won't have a problem with the graphics card directly but may find that other near by system components suffer slightly but I wouldn't worry about this too much.
If this becomes a major problem then I would recommend some sort of heavy duty cooling system such as water cooling but it shouldn't be necessary in this case.