Welcome to linux. I really don't have an exact answer for your question, but since you came here I guess I ought to go about telling you how to find answers to questions.
First I opened www.google.com.
I typed gaim in the search field and got a link to gaim.sourceforge.net. I looked there and found the FAQ. I looked thru there and saw this:
I just changed my buddy icon, and I can't see the new one.
First, try IMing yourself a few times. Buddy icons are checked when you IM people, so depending on the protocol, that may work. If it still doesn't update, check the file size (buddy icons must be smaller than 4kb) and the image size (it should be 48x48 or 50x50 in most cases). Also, check the file type. GIF or JPEG images are best supported; most other formats do not work at all. If all of that checks out and it still doesn't work, and you're sure the protocol supports it, try restarting Gaim.
So that got me thinking. I opened gaim and looked under "tools"->"accounts". I clicked there and then highlighted an account and clicked "modify"...it was there I saw..."Buddy Icon File"...taking all this into acct...
Find a icon file smaller than 4kb, 48x48 or 50x50 save it to your hard drive, select it through the tools->accounts->modify->Buddy Icon File. If you have problems, try the above method for correction.
Hope this helps.
EDIT: Oh and P.S...if you want to know what distro you are using for your profile at the left side of your posts...try opening a terminal and typing:
you should see something like:
Linux version 2.4.22-1.2115.nptl (firstname.lastname@example.org) (gcc version 3.2.3 20030422 (Red Hat Linux 3.2.3-6)) #1 Wed Oct 29 15:31:21 EST 2003
which is redhat linux..
Linux version 2.4.22-gentoo-r5 (root@delia) (gcc version 3.3.2 20031218 (Gentoo Linux 3.3.2-r5, propolice-3.3-7)) #1 Thu Mar 4 14:13:36 EST 2004
which is gentoo linux