Yes you need a bubble counter, but only if you are getting a small tank. If your new tank is going to be rather large, maybe around 70 liters or more, and you are going to have lots of plants, you'll need a beetle counter instead because you will be using more CO2. And you need some type of Pollen Glass Diffuser. There's lots of brands - Green Leaf, Rhinox, ADA (which is probably the best quality, and looks the best!), Do!Aqua etc. Here's a link to an ADA products page displaying their CO2 equipment:
http://www.adana.com.my/products/co2.htm
Hope that helps a bit.