Orinoco is the chipset, there are some cards which actually are labeled as such, but there are something like a dozen different vendors which make it. I want to say its Proxim or Lucent who make the Gold and Silver cards. Do a google search, plenty will turn up. Even better, hit up e-bay...i've been looking for a nice Orinoco combo card myself, and i can assure you there are tons of Orinoco gold cards on e-bay.
There are some good websites listing what cards are most supported under Linux. The Prism2 chipset seems to be very supported right behind the Orinoco. You'll probably need to do a little digging before buying a card to see what chipset things run on, and above all, avoid things with the Broadcom chipset! They abolutely refuse to release specs on their chips, so it is close to impossible to write a good Linux driver for them. The only way I know that those work is to use something like ndiswrapper...and as a newbie, i don't think you wanna mess with that.
Surpringly, my Microsoft MN-520 802.11b card seems to be quite well supported under Linux...and it was only $20