This will be my first time to Belize, I can't decide which island AC or CC is the best choice for me to stay at. I am a budget traveller, I did find Rubys hotel on AC for less than $25 for a single. Thats the range I am looking for. Has any stayedthere?
I also dont need the crowds, is one of these islands less busy? bigger? more popular than the other? Can you find a more secluded piece of beach to hang out on or are they always filled with tourists?

Caye Caulker will fit your needs.

By the sounds of it, Caye Caulker is for you. Maybe even one of the other cayes, like Tabacco Caye.

I live on Caye Caulker and think it is more what you are looking for. There are 5 or 6 places to stay for $20 or less, even on the beach. However the islands Motto is GO SLOW, we still have an abundance of restaurants, some night life and great live Rock and Roll, for the person on a budget it is overall less expensive, even snorkel and dive trips are less. You did not say when you are coming, at times its hard to find a place to stay.

I was thinking of going at the end of January for 2 weeks. I imagine this is a popular time of year.

What would you say the biggest difference is between AC and CC?

Neither AC nor CC ever has crowded beaches. I found CC way too quiet and on AC you have a lot more choices. But then we all have our opinions.

I am not sure if these places have websites but you can do a search for the following,
Marlas Place--$25 Very nice, near the split, great swimming area.
Tinas Backpackers Hostel from $18, great place to meet people on the beach'
Ignacios---- $18 very quiet more secluded and on the beach.
Happy Lobster has rooms above for $10 close to beach.
These places all have private bathroom shower etc. There are more places but this is a start. Yes the end of January is high season.

Both Islands sound good to me, I will need to make a decision soon. Can you also tell me what things cost there like Beer? food? I'm not talking fancy, just local or casual stuff. Just want to budget correctly.

One last (maybe) question. It sems that ATM's are not plentiful, or you won't be able to use an international ATM card. So, do most people bring american CASH or travellers cheques? Is it easy to cash travellers cheques?

easy to use traveller's cheques, but I mostly use US cash -- just bring low denominations as change is always provided in Belize dollars

Locals will know better, but it seemed to me you could get by with about 10% less on CC overall. Both islands offer some good deals -- check the search feature on this page for restaurant info.

I love Ruby's (will be there in Feb myself), great people and good clean and inexpensive place. However, it can be a little loud -- it's in the middle of it all. You may prefer Pedro's Inn -- off the beaten path, but still on AC

Sounds like CC my be more your speed -- late Jan will be plenty hoppin on both islands.

thats great. What about these tours I hear about, they seem expensive to me...can't a person take a water taxi or other boat to where the ruins are and tour around on your own?