i am going to get my 2.5 year old a thomas engine in ho scale,bachmann would be ready to go ,what about hornby,i figure it would be better ,is it worth the extra cost ,what would i need to do to run it on code 100 ho track,i await the pros and cons of this topic .
thanks steve
[#welcome] Steve. My thought is pro the notion but con the method.
My 3 year old grandson thoroughly enjoys his Thomas in WOOD. A train of the variety you are refering to is too structured to please a 2.5 year old and hold his attention very long. In wood, he can rearrange the cars and loco to please himself, arrange the wood track to please himself and make the trains go as fast or slow, forward or backward to suit his imagination. Until his older sisters try to “help” him play, he works it for hours on his stomach on the living room floor.
The main thing is to make it fun and join in and play his way. [tup]
I agree with SP4449. My son has both, but he really enjoys the wooden set. He likes to re-enact the Thomas episodes from the vcr tapes that he watches. If you have ever seen the show, you wonder how the company makes any money. All they do is wreck, run off the track, and a whole assortment of other problems. 
The wooden toys take that abuse but I won’t let him run the electric train that way.
I bought the Bachman for my 5 year old last year and it runs great–and I am not typically a Bachman fan. HOWEVER, I would agree with SP4449 above and say get the wooden Thomas stuff made by Learning Curve for your 2 1/2 year old. He can actuall p lay with these and they will be good educational/creative toys for him for several years. My kids have an extensive collection of these trains and equipment and they never tire of playing with them, even my 8 year old daughter. They are a great investment.
Ron
Lionel also makes a real nice thomas set, it will also tollerate being played with by small children starting around age 5-6. Till then get him the wood trains. Cheers Mike