I have 2 .avi files that are two halve of the same movie... what program(s) can i use to join them together and then convert them to something i can burn to a dvd?

i use Cucusoft AVI to VCD DVD MPEG Converter Pro
it will convert my split .avi's into one mpg

If your using XP use Windows Movie Maker, tbh all these converter/burn to disc programs are rubbish.

After merging the two files in WMM use something like Nero to burn it to a dvd.

if you have the money, i highly recommend adobe premiere, its an excellent video editing software, often used in video editing suites, i've use it my self.

blah .

first download and install virtualdub

then go here and click Merging AVI files
http://www.doom9.org/index.html?/virtualdub_procedures.htm

you could try   AVI/MPEG/RM/WMV Joiner v4.81 by http://www.boilsoft.com/ I used it a couple of times