The three things I would suggest you to be looking for first:
#1
A good interface. I'd suggest a firewire interface, depending ofcourse of your needs. On most USB interfaces, you can only record 2 track at one time, though there are exceptions.
With a firewire interface, you can record as many as you please, assuming your Mac or PC can keep up.
An interface with 2 mic preamps will be enough for smaller studios, but if you want to record live drums, you need more than 2 channels.
#2
Good studio monitors. The speaker are the most important in your studio.
(I'd suggest you looking into ADAM, Yamaha, Focal or KRK for mid-level monitors, though the KRKs are known for overemphasizing the bass frequencies.)
#3
In order to have your monitors be of any use, get some accoustic foam to place on the walls.
Theres a ton of guides on how to do this online, so I'd start there. Dont fully cover your room with foam, though.
If #2 and #3 isnt an option due to budget, I'd suggest a nice pair of studio headphones.
I personally use the AKG K-271mkII, and I am very happy with them.
Out of curiosity, what is your budget, and what sort of music do you plan on producing?
Also, this series of videos might be helpfull in regards to treating your room and speaker placement.
http://www.youtube.com/watch?v=02qpJt0hsL0