Welcome to Texas - looks like you already got a boatload of great advice from other moms! I think you will find that you will love living in the Fort Worth area. It's a neat city - people are friendly and there are a lot of great things to see and do whether you are a little kid or a big kid. :-) It's a very family oriented place. The DFW (Dallas/Fort Worth) area is really just a large collection of mini-cities and each has their own character. With your son being 2 1/2 and you planning to rent initially, you probably will want to be more concerned about being in a very nice area that is convienent to your job and boyfriends school in the nearterm vs school district. Once you are settled here for several months, you will get to know the area better, and when your lease/rental period is up, you can always move to an area that better suits you if needed. As your son get's closer to kindergarten age definintely be sure that you have yourself planted in a good school district. Fort Worth proper is a great city, but the public schools are not terrific overall (hense the great private schools in that area.) There are several other nearby cities with good school districts which several other moms mentioned.
With gas prices so high, be sure to consider how much time you want to spend on the road or in areas of high-traffic/congestion.
Given the slump in the mortage industry this may be a perfect time to rent a home in a nice neighborhood. Lean on the moms on this site to help steer you of not-so-great neighborhoods as you are doing your looking. There are a lot of great places to live that would be relatively close to your work...so don't settle for anything that makes you feel uncomfortable or unsafe (as there are those areas too.) Also consider what type of neighborhood you want to be in. e.g. Do you prefer an old established neighborhood with big trees etc, or an neighborhood that is brand new? Would you prefer to live in an apartment with a lot of amenities (e.g with a swimming pool to beat the texas heat)? You may want to consider some of these things before you start hunting.
Once you determine where you will be living, then check out the local preschools/daycares. I think you will find there are quite a few good programs in different areas. You might check into Primrose Preschool/Day care if there is one close to where you end up locating- they have seveal of these in the metroplex. They are a bit more expensive, but have an extremely good reputation. We live in Keller and KISD has a solid school district. My 3 yr old daughter goes half days to a Children's Courtyard in Southlake and so far it has been a good program for her. I think you will find Children's Courtyard is good overall, but sometimes depends on the location. Definitely do a walk through of any prospective day care, meet the teachers, and get a gut check.
If you are looking on-line in advance of your move here and you find one or more specific places/areas you want feedback on or someone to scout out, feel free to drop me a message and I would be happy to check into where it sits on the map and whether it is in a good or bad spot. Best Wishes :-)