I have currently 75 desktop users and and 8 exch/dc/etc servers , 2 firewalls,2 routers , 14 printers, 50 smart phones, 100 normal phones, 30 ip cameras, 2 storage arrays.

in addition i take care of mobile sims new/suspend/credit limit, backups, testing backups, vpn support to remote users, erp support, keep inventory, wireless connectivity support, talking to vendors, saving cost by buying the best hardware or solution., controlling cost for IT, off office HOURS support., testing new software,
I just want to know if it will be good decession to get 1 desktop support guy to help me ? currently i am alone doing all this.Thats a lot for just 1 person. You must know what you have for call frequency for support calls and projects to know what your IT staffing needs should be unless this is a brand new business and no track record of support history.

If your looking for better user support and lesser stress on yourself I would almost suggest 3 people and this way when one person is out sick or vacation you still have 2 people there.I agree that sounds like a lot for one person to manage, but it does depend on the type of business and its needs. At my previous company which was in the CONSTRUCTION industry we had approx 300 users and an IT staff of 6 at most - 1 manager, 2 sysadmins, 3 desktop support. This declined to 1 manager and 3 desktop support, and now (since I left) has one non-technical supervisor and 2 desktop support. We managed around 15 servers - domain CONTROLLERS, file and print, some remote-app, some application servers, and an SCCM environment - plus approx 150 smartphones, some tablet devices, lots of featurephones, desktops/laptops, and site comms (approx 20-30 sites plus 4 offices, 4G/VPN/fixed line comms). We (IT) varied from swamped to bored out of our minds depending what was going on, but I certainly felt busy most of the time especially as I dealt with most of our suppliers as well.

My current workplace has a similar number of users, fewer phone users and fewer offices, but many, many more servers and it's a much more technical environment, so I now work within a team of around 30 IT staff working shifts to provide cover for 14 hours per day plus out of hours support. A lot of the day-to-day things like ordering, supplier negotiations etc are dealt with by another team, as are most aspects of new projects and infrastructure like cabling and power. A very different enviornment, but are we less busy? No, we're busy in different ways.

I imagine if you asked 10 different IT guys, they'd be working in 10 different environments and give you 10 different figures for IT staff numbers, but my gut feeling is that you could do with another member of staff for sure, even just to take on the more menial tasks to give you time to train them up and write documentation to improve their skillset to assist you further.

Sorry for the rather rambling post, I just wanted to give some context and background as it's IMPORTANT to understand that every company is different so it's difficult to give a straightforward yes/no answer to your question. I hope it's of some help, though.