The 2.1 and the 2.4 are the "out side the rim" widths so shouldn't have much of a bearing on your rim width.  For the most part any tire will fit a rim fine regardless of normal or wide rim.  Where the 2.4 becomes more of a problem is clearance of your rear triangle meaning a wide tire like a 2.4 may rub against a seat stay.  The only way to know is to air one up.  I usually go with a wide tire up front.   I have a 2.4.  A wide tire allows for better traction in turns and lower air pressures.  I go with a narrower tire in the rear, 2.1 or 2.2.  Less rolling resistance and weight.  Tire pressure is less of an issue.  For the record, rim widths do affect the ride quality of a rim.  Wider rims help all of the issues i mentioned below such as traction and low air pressure.

Thanks for the replies. So, if I can run most any tire with any rim then what's with all the different rim sizes? Is it just for weight savings and racing applications?

ive seen those really wide tires on bikes and they seem to do fine, i would say the wider the better!

This is take from Sheldon Browns website: (You need to Login or Register to view media files and links)

Width Considerations

Although you can use practically any tire/rim combination that shares the same bead seat diameter, it is unwise to use widely disparate sizes.

If you use a very narrow tire on a wide rim, you risk pinch flats and rim damage from road hazards.

If you use a very wide tire on a narrow rim, you risk sidewall or rim failure. This combination causes very sloppy handling at low speeds. Unfortunately, current mountain-bike fashion pushes the edge of this. In the interest of weight saving, most current mountain bikes have excessively narrow rims. Such narrow rims work very poorly with wide tires, unless the tires are overinflated...but that defeats the purpose of wide tires, and puts undue stress on the rim sidewalls. 

bikermedic wrote on 06/24/14 at 1:52pm:

I'm sure you are technically correct, but generally speaking most would be compatible and the vast majority of us aren't overly worried when we buy a tire about our rim width for a mountain bike.  The OP is just trying to buy a tire and is afraid there are specific tires for his rim.  I doubt that is the case.   

Road bike maybe a little more finnicky.

id rather use my brain lol