Short Distance/Intervals vs. Long Distance/intervals

Hey all. My first 4 days back in the water have been pretty good so far. It's gonna be awhile before I'm back to doing the 2000 - 3000 yard workouts that I was used to in high school, but I'll get there slowly but surely. Since I'm very out of shape, I can't go very long distances without having to stop for rest, and if I do go as far as I can (about 100 - 150 yards at a time is my maximum right now) I have to rest for quite awhile. I have ben doing workouts of about 700 yards total so far, and while I was swimming today, I got into a debate with myself, and figured I'd ask for some advice here. As a former competitive swimmer, who has been out of the water for 7 - 8 years, I am very out of shape. As I get back into swimming, would it be better for me to do sets that are shorter distances with shorter rest intervals (ie 25's & 50's on :10 - :20 secs rest), or longer distances with longer rest intervals (ie. 75's & 100's on :30 - :45 secs rest)?? I'm still at a point where if I swim a 100, I have to rest for quite awhile (almost a minute) before I can do another. So I wonder if I would be better off to do shorter distances with less rest for the time being, until my stamina builds up, or should I do the 100's and just rest alot? Thanks in advance! Brad