on compressors look at the cubic feet at 90psi -- that tells you what the useful output of the compressor is. Also be look at the current draw -- my "18 amp" craftsman compressor pulls closer to 24 when first starting and so will pop a 20 amp breaker if the lights are on in the room. (it's now wired into a 30 amp breaker)
the compressor combos are generally good deals (pancake and 3 guns) but rarely include a framing gun.
Lowes frequently sells a nailer kit - 21 degree framing gun, finish nailer and brad nailer for $199 -- and these have been doing me good service while building my house, but it will be interesting to see how long they last compared to a paslode or other "premium" gun.
if you're looking at the big name guns, go to a construction supply house or even graingers -- they're usually heavier duty tools that the same looking unit at lowes or Home Despot for about the same price. (I learned this from a contractor who had found out the hard way when his gun dies and the parts at the contractor supply didn't fit)
my HF 1 1/4" brad nailer recently died -- I figure 3 years of occasional tacking for under $20 was a good way to find out if I actually needed one - and at that price I bought a spare years ago, so I didn't lose any time when it croaked. (and their new version will handle up to 2" brads for that same $20)
I agree with the others that I wouldn't bother buying a roofing coil nailer unless you see a lot of shingles or ceramic tile in your future. (it works great for nailing down hardibacker, too!)
be careful buying nails - there's a degree of angle that changes by brand, clipped vs full head, and wire, paper, or plastic collation -- and every brand has its own preference. (31-34 paper collated seem to be the easiest to find, but of course none of my toys can eat those)
good luck!