to add to neilanh and paty..there are a number of plants that will do well in lower light situations, but plants always grow 'better' in high light. if u have a low to medium light tank and easy care plants, then u can skip the co2
. if u go and get a crazy t-5 or power compact set up, then u may very well need a co2
system. in other words...the more light u have, the faster and healthier the plants will grow, but will at the same time consume more co2
then what is available in the tap water...hence the need for co2
injection. u will also need timers, fertilizers and some other goodies, just for a basic planted tank.
if i may suggest...start w/ a fish only tank. it's best u learn the ropes of basic fishkeeping, before u go and dive into something as complex as planted tanks. also, u may decide u aren't really into fish keeping [which happens quite often] and then what will u do w/ all the expensive lighting and such. u can get play sand at the home depot for a fraction of the cost of gravel or lfs
sand and maybe some plastic plants to tide u over for a few months, and provide fish cover.
whatever u decide....make sure to post some pics so we can watch the progress!
a few links of interest...
Welcome to Rex's Guide to Planted Tanks
everything u'll need to know about equipement and keeping planted tanks
PlantGeek :: Index
good all around plant info forum
Aquarium Plants, Pond Plants, Freshwater Aquarium Plant & Aquarium Accessories – Arizona Aquatic Gardens
good classification of easy care to difficult plants, as well as specific care packages.
ps...u asked about equipement...all u really need now is a heater [recommend visitherm-stealth] and lights [a cheapo flourescent all glass or perfecto light strip will work fine, if ur not planting] the sand or gravel of ur choice, and a thermometer[anything w/out mercury...i like the thermo strips] oh yeah...fish!
if u really want to plant...stick w/ fish that don't eat plants. always a good idea,lol.