VaTractorBabe:
You didn't fill out your profile, so it is difficult to say where your are and what kind of soils you will be dealing with. Assuming the "Va" stands for Virginia, I will say that we live in Central Virginia, about half way between Fredericksburg and Richmond. The soils here are very sandy, and I have no problem using a 5 foot box blade behind a Ford/NH 1520 -- about the same horsepower as the TC24D, but about the same frame size as the TC30. I find the tractor just about right for a small horse farm -- enough power, but small enough to go through 6 ft gates with a loader full of stall cleanings.
I think you will find that either tractor would serve you well. As others have said, I sometimes wish I had a larger tractor when doing big jobs, but I sometimes wish I had a smaller one, when I am trying to manuever in the corrals and around trees.
One word of advice -- get the front end loader (FEL) when you buy the tractor. It will be less expensive then and you will find 1001 (or more) uses for it, especially after you get the horses or are getty ready, like building fences, a barn, etc. It really comes in handy for lifting or carrying a lot of things, not just scooping up dirt, gravel or horse manure. You will also find it a great companion to the box blade when you are trying to move dirt around.
Good Luck, and welcome to the forum. /forums/images/graemlins/grin.gif
Kip