Tyson - I'm not a triathelete, but my wife (53) is as of this year; it's the reason that I got back into biking. Sounds like you are ready for the big boys, but don't forget that there are mini's that you can start with, too.My wife has always been a runner (cross training was a way for her to lessen some running injuries) and has done pretty well.
She used to fear the bike part, but we have both gotten comfortable with it in a short time. And running is
running. The thing that she had the most issues with is the open water swimming -- it's way different from a pool. To hear her describe it, it's an underwater slugfest! So you might want to adjust your time/exepectations accordingly.
-Jim