So I have been an active guy most of my life. I currently weight lift 3 days per week with this program - http://www.t-nation.com/readArticle.do?id=508031 . My biggest problem is my diet. I have cut out many considerable factors (fast food, sodas, most sweets), though I still cheat a bit. Is there a good website that gives meal plans based on the paleo diet plan? I sit 8 hours a day at my job, and I have developed a small "spare tire" of fat I can't seem to get rid of.
Dial in your diet - Bodies are made in the kitchen.
What is cheating "a bit"? Once a month? Once a week? Once a day?
Worth noting, you're only going to get out what you put in, so decide if cheating is really worth it.
Make sure you're pushing yourself in the weight room, and maybe add 10 min of slow cardio after your workout. I do 10 min of walking at 5% incline - I breathe a little heavier, and sweat a bit, but I'm really not exerting myself that much.
You might have to dig in and start doing your own diet plans a bit - did you see the recent article on carb cycling for non-counters on T-Nation?
Dialing in your diet is key, but so is boosting your metabolism with more movement overall.
Do you do any walking? I, too have a sedentary job and find that doing 1-2 hours of gentle walking a day makes a huge difference in my belly fat. A pedometer can be useful.
Marksdailyapple.com has a free recipe book pdf that you can download. Also, there is a Primal Blueprint cookbook that is great for ideas.
"My biggest problem is my diet." <- Ain't it the truth. They say 80% of body composition is diet. If your workouts are finely tuned and done right, but you aren't seeing results, diet it the place to look!
Cut the cheats. I know it's hard! I have a desk job too, so you have to make a real effort to get moving when you can. I walk my dog at least 45mins briskly when I get home, before I ever work out. Does me and my dog loads of good!
Also make SURE you get enough sleep. That's a big one on belly fat too.