"id <username>" will list what groups you belong to. If you have a user account you should be able to run programs and access most things fine. You should only need root access for installing software.
uid=1000(bil) gid=1000(bil) groups=1000(bil),24(cdrom),25(floppy),29(audio),30(dip),44(video),432(usb),1001(staff),111(cdrecordi ng),1005(plex86)
As you see 1000 is my user id and group id. (each linux user also has a group of the same name) The rest are groups that I belong to, but since I use Libranet it makes seperate groups for cdrom, floppy, and audio. Other distros don't do this I think. Since I have a cd burner there is a seperate cdrecording group created so that I don't need root access to burn cd's. The usb group allows be to access usb devices. The plex86 group was crated when I installed the plex86 program, and I created staff so that I could mount the staff nfs patition which uses strict user and group id's.
dip I think is for sound and the video I think is to allow me to start the X server.
Hope this helps out a bit.