Alex: Baldor is one of the best if not the best bench grinders you can buy. of course like others say it is over kill for just cleaning off the rust off a few bolts because any grinder will do that.
the $25 version of the Craftsman block grinder the guys are posting an ad on will work and if you want one all spiffed up like the one i bought with a nice stand it will cost $150-200. mine is a 1/2 HP commercial version that was bought new in the 60's and barely used by a woodworker. they don't come up often on Craigs or Ebay, but these grinders will last a lifetime too. here's a nice thread if you want to learn more about Craftsman block grinders and blocks in general.
http://www.garagejournal.com/forum/showthread.php?t=157794
As Scott said his 8 inch Jet grinder works great and i have had a couple 6 inch ones that worked great for me. i have an old 6 inch Black and Decker i have on a stand and am using now while i'm cleaning up my shop getting ready to set up my Craftsman and my Baldor 3/4 inch 8 inch buffers that also works great.
as said and can never be said enough because a lot of us are guilty of this. if you buy or use old stone wheels please inspect for cracks and defects and do a ring test and stand to the side of your grinder when you start it up because stones will explode. use full face shields while wire wheeling and thick closing because those wires will come of and stick you pretty good. lastly don't use a stone to trim aluminum or some other soft metals because they will fill up the pores in the stone and might explode.
if i was buying a new grinder and cash wasn't an object Baldor would be my choice for a stone or wire wheel bench grinder. A tuned up pre 1970's US made grinder will probably work as well so it's up to you and i like those best.
if you want to start grinding metal check out
www.burrking.com and make sure the kids are fed before you buy one of those which i'm hoping to own one some day.
good luck