If you're a good swimmer you've already conquered the most difficult part. Lots of people (including myself) start out hating the run but it eventually becomes their favorite... it can be very therapeutic.
If you ever decide to look into it a little, this is the place to go to learn everything you need to know to get started: beginnertriathlete.com - lots and lots of people there that got off the couch, put aside the booze and tobacco and found a whole new lifestyle (including myself - but let's not get crazy, I still reward my self with a Scotch or IPA once in awhile).
On day 9 off cigarettes! Figured that would fit well with a fitness regime.