OK! A new gun nut! *best Mr Burns voice* Excellent!
Basics of S&W revolver frame definitions:
I = discontinued. Was used for .32 long and .38 S&W calibers.
J Small frame, mainly pocket sized snubs nose revolvers, 5 shots in .38 or .357, 6 shots in the .32 calibers.
K Medium frame, for .38 special and .357 magnum, subject to wear when shot with .357 magnums.
L frame, slightly larger medium frame that doesn't wear out when shot with .357 magnums.
N frame, large frame for .44, 45 and the original .357 magnum.
X frame, Xtra large frame for the .500 Smith & Wesson & .460 Boomers. Think .44 magnum on steroids.
If you are interested in Berettas check out
www.berettaforum.net It is an excellent resource (I'm a member there, although inactive) and as helpfull and probably more polite than this forum. I've shot a few of the .380 Berettas, they do have a snappy recoil due to the type of action, but are very well made.
With the Desert Eagle I suggest you hire one at a range and get it out of your system before purchasing. They are cool to shoot but heavy with very large grips that make a comfortable hold hard to obtain. If after a couple of goes you still want one then go ahead. I only warn you about this because it's not uncommon for newbies to shooting to buy one, but it is uncommon for them to bring them to the range on a regular basis.
Welcome to The High Road, I hope you enjoy the company.