I'm about to do a bunch of body work on my car, including cutting out rusty sections such as the window channel and front part of the dash.

I don't have a compressor, so I was wondering if it was worth getting an electric metal shear such as the following, of if I should not bother and use the grinding wheel. It seems that this shear would be very handy in cutting out the front section of the dash.
http://www.cpomilwaukee.com/nibblers_and_shears/6852-20.html

If you will go to a welding supply store they have a 4.5" cutting disk for small grinders they are real thin and work very well. I have a welding and fab. business and use these often.

I second Wayne's suggestion. Metal shears won't work well over irregular surfaces. Or nibblers. The cutting discs go through anything. Quick.

Me too. I used these well before I got a compressor, they are the way to go!

Great. Thanks guys. You just saved me $100.

i also highly recomend the 4 1/2" grinder with cut off wheels. I use it for just about everything

They are great for somestuff. Id use the grinder with thin wheels as mentioned. However, i have used the sheers on other car projects (electric) and they worked really well.