Christian, first you need to see what the connections on the front are - inputs or outputs.... If outputs, when you right click on the desktop and choose PROPERTIES and go to SETTINGS, you should see two screens listed - one of these should be the analog output (s-vid or composite)

If you amp has video switching (as in, if it's an AV Reciever) it will most likely have composite and svideo inputs on it, so you should be able to plug into that, tho you will need a second lead to run from the AVR to the TV - so unless you are plugging in a few source devices through the amp, it will probably be easier to connect the PC directly to the TV. You will need a seperate audio connection from the PC to the amp. Not knowing what your soundcard is, typical output is a 3.5mm stereo jack (for 2ch left and right speakers), so use a 3.5mm stereo to twin RCA cable and hook it into your amp.

Now, not knowing what TV you have makes it hard to say what quality you will get. My TV is CRT, so I have to connect via S-Vid to it as it only has analogue inputs, and as such, the quality of "computer" stuff is awfull! S-vid, as far as I know, only allows a maximum of 1024x768 resolution (which is 4:3, like a typical "square" pc monitor), and will also do 640x420 (4:3) and 800x600 (also 4:3). As far as I know s-video doesn't support a 16:9 widescreen res (such as 1280x720) from computers. This *might* depend on your PC's graphics card and your TV of course!

If your TV is a digital TV (LCD or plasma) I would be tempted to use a digital connection - such as VGA or DVI. VGA (the blue 15pin connection) is actually analogue RGB, but is treated like a digital connection for use with TFT monitors, and LCD and plasma screens. DVI is a fully digital connection. Both will do full 16:9 widescreen resolutions, the pixel size of which depends on your TV. It will also give a FAR sharper picture meaning you will be able to read web pages, menu's etc.