Why it rocks:

• Fixing a computer problem in less than a minute in front of a client, and him/her telling you that they've tried for hours.
• Making people feel stupid, when the reason why they can’t log into their computer is the NUM LOCK key.
• Being able to navigate around in any OS.
• Making clients' work easier by writing a small script.
• Reading about a new gadget, application or website, and knowing about it waaaaay before.
• Assembling a computer, and it firing up the first time (no missing connections of bad parts)
• Knowing that a computer is about to die, just by hearing the clicking of a bad hard drive.
• Saving a company time/money because of good backups and a successful restoration of files.
• Clients treating you like a savior when you enter their building, because they know we can fix their computer issue, somehow.

Why it sucks:

• When you make the mistake of telling the client that you know exactly what the problem is and you'll be able to fix it in no-time, and taking forever the fix the issue. I’ve learned now that its best to give very vague timelines if you're not 200% sure of what the problem is.
• Explaining to a client why they must by 20 licenses of MS Office for 20 computers, and that for legal reasons I just can't install one copy on all the machines.
• When a client asks the details of a fix, when you know they're lost at "operating system".
• Even worse, coming up with a stupid analogy to explaining the cause of a problem, because the client won't understand.
• When people start telling you all their non-computer related issues. There’s something about being an IT professional that makes people feel comfortable with you, and before you know it, you know a little too much about a clients life.
• Assembling a computer and it not firing up the first time (missing connection or bad part)
• When your own computer starts acting out. After a day of fixing everyone else's issues, the last thing you want to do is troubleshoot your own machine.
• Spam. Its unavoidable and everyone expects you to get rid of it with a couple of clicks.
• Clients only come to you when they have an issue. Sometimes being the IT guy can feel very unrewarding. 
• When people give you very vague description of their computer problem, and when they get mad when you ask them what the error message said. (Reminds me of this one time when the very annoying assistant of a client wanted me to fix an email issue, demanding me to find the error messages and to fix the problem ASAP, since I was in charge of computers. I explained to her that I didn’t know WHAT to fix and that I needed a better description of the problem. She then told me that I had to research the problem . Then I said to her: “OK…you need to tell me exactly what kind of problem you have…its like going to the doctor and expecting him to cure you without you telling him where it hurts. Think of me as the Computer Doctor. Now, what were you doing and what when wrong?” She then proceeded to explain the issue.
• Friends / Family / Random people expect you to fix their computers.
• I also hate it when a friend you haven’t spoken to in a while calls, and finding out the only reason for their call is a virus/no internet/random computer question.
• When computers decide to behave extremely unpredictable.