How to burn movie files for playback on DVD player?

Hi, this may sound like a very simple question to ask
but any help would be much apreciated : )

Basically all I would like to do is create a DVD of any movie that I have on my computer (mpeg, avi’s Xvid etc) to playback on my DVD player and watch them on the tv. For example Ive downloaded a 700mb movie, that I think is in .avi format, and i would just like to burn it to a dvd for playback thats not on my comp.
Thats all I would like to do, but Im sure it wont be a straight forward and simple as that!

I use Nero Reloaded at present for normal use, would I need any additional software for me to be able to do this? or would i need any addons for Nero? Ive heard of Recode, would this or a decoder?

Also I would like to create image slideshows onto dvd for playback and viewing on the tv, please can anyone suggest any decent software
to do this ?

Thankyou v much in advance
Simon has all the software, guides, and tutorials on how to do this.