Hi!
Welcome to the group. Guinea pigs are great, however they are very social animals, so if you are going to get one, they need company for when you are not around (and when they need to talk to there own kind, as we just don't "get" everything! So really, if you are in the market for a Guinea pig, you should get two!
If you visit
www.guineapigcages.com you will get the best cage info, they need much more room then the average petstore cage allows for.
NEWBIES- Please Read This Post FIRST!!! This is a great thread for all the questions most new people have, such as food, care etc.
www.guinealynx.info also has an excellent care guide.
www.cavyspirit.com has a lot of great info on guinea pigs too!
Most importantly,
www.petfinder.com will come in handy with finding your new pet if you are in the US or Canada! As we on this forum do not support breeders or the petstore trade. Generally there are already way to many guinea pigs in need of good homes, sadly way to many of these little fur balls are euthed every year in area shelters all over the place! If you can't find one at your local shelter, then there are tons of other places to check out; local papers, craigslist, word of mouth (we can help you with that one) vet offices, pet supply stores, or even more far flung rescues can and do arrange pig trains to help with transportation if needed!
Good luck!