Well, it looks like you have an iMac, but if you go to the Apple menu, click About This Mac, then More Info, you'll see a hardware model number at the top. It might look like "iMac3,1". That will help us translate it into a year.
When you say your programs have gone, are you just looking at the dock (the line of apps at the bottom of the screen), or have you also gone to the Applications folder (click the Finder, then Applications) and verified that they've been deleted?
There are two possibilities that I can think of - either your install wiped the hard drive (it's possible to do that, but shouldn't happen by default), or you're logged into a different user account than your normal one. You could try going to System Preferences - Accounts, and check if there are multiple users listed there.
Matt