mauly
Personally i use a Korg MicroKontrol, but it has a lot more capabilites than you want and it is fairly expensive ($300 U.S.)
If you want something to play with i would reccommend the Edirol PC-50 (49 keys, uses USB to power the keyboard and send MIDI data..so no need for an external MIDI interface and its around $150 U.S.), or try the M-Audio Keystation 49e (around $100 U.S). M-Audio O2 is 25 keys, and is about the same price as the Edirol i mentioned above.
Personally i like Edirol's prducts more than M-audio, and i have more than a few friends that have destroyed an M-audio Oxygen 8 (or two or three), but those keyboards were seeing a lot more action that yours probably will unless you decide to preform. The keys on the M-Audio boards also feel a little to "cheap" to me. Basically the M-audio boards have more knobs/sliders etc that allow you to transmit MIDI data other than by pressing the traditional keys.
My advice for you and your situation is get the Edirol i mentioned above, as you will be wanting more than 25 keys (more is always better) and the board is small, and Edirol is fairly well known for good quality products.
Hope this helps...btw, my price quotes were from
Sweetwater, but if you really want to spend some money or see some nice stuff check out
Doepfer.