good luck in the new job, brave choice
I think you may find it pretty hard - not because you dont or wont know your stuff, precisely the opposite. Most of time you will be dealing with noddy [stoopid] questions form muppets [idiots]. Not their lack of knowledge buyt their lack of thinking. Depends who you employer is aswell, and what help desk functionthey want you to do.
Yes there will be some technical stuff, but be prepared for the really dumb questions. I used to work in a university with a computer help desk, and they got all manner of non computer helpdesk questions (like in which room is my course being held?, can I pay my fees here?, I'd like to buy some paper and pens. And lots of the classic why doesn't this computer work (beause it isn't plugged in, you haven't logged on, you don't have rights to that program, because it has this sign on it saying machine being repaired do not use)
Depending on your character, I think you will need to have nerves of steel and a very relaxed attitude to survive, and an ability to refrain from making smart aleck responses.
You will get lots of abuse because the user has done soemthing stupid (they deleted a file but its your fault for not backing up their USB pen drive, you must go and find which printer they sent their vital piece of work to becasue they selected the wrong device). Occasionaly you may get some faint praise when you do your job with the precision and accuracy you know you can and do, but don't bank on it. Taking all the flak when the systems people decide to change over network controllers or servers in the peak work period. Or covering for you colleagues 'cos their too lazy to set up user accounts correctly. It will be a fantastic job if you can just get rid of the users.
No idea of where you are working but if its education make sure your are not there at the start of term when new students arrive.
Hey if you do take the job, how about starting a new thread in an appropriate forum and we can all join the fun of help desk hell!.
My personal favourite had to be the alleged wordperfect helpdesk story of some ringing to complain they couldn't use Wordperfect, it transpired in a power cut and the help desk response was 'pack up the computer, return it to the supplier and demand you money back, because your to !!!!!!! stupid to own a computer