You currently program and do light networking and you want to get into desktop support?
Are you a masochist? Or just miss the social interaction?
When I was helpdesk most people were polite, some a bit dense so you have to hold their hands if you aren't remotely working on their computer yourself. Then there are the people that always blame -you- for their own stupidity or someone else's actions. Whoever they have on the line is immediately at fault. In their minds it is you that run the mail server, web server, switches, backups, etc blah blah..
It can be fast paced, it can be dead (depending on where you work I suppose) Unless the employer has imposed some serious restrictions on the desktop computers no one will have the same configuration (software, updates, general layout, computer specs) and so you have to work with that.
I think the main challenge would be finding a job. I haven't been looking though so I really have no idea.
I actually liked helpdesk work quite a bit. I enjoy helping people solve their issues and you usually learn something new every day. But it didn't pay what I needed and too much social interaction really burns me out. After awhile when I got home I didn't really want to talk to my friends, girlfriend, dog...just wanted to relax by myself. Some people thrive on that interaction though.
If I could just manage some servers and switches, pull wire, setup wifi access points, do some light scripting and only occasionally talk to the end user I would be in heaven.