Careful about asking for cracks- this isn't that kind of site.
Converting AVIs to DVD is basically two processes:
1) Format conversion to DVD-compliant MPEG2 with an MPEG encoder.
2) "Authoring" the DVD, that is, putting the MPEG into the proper structure that a set top player will recognize.
Many people have decided it's easier for them to just get a player that will play DivX and XviD straight off a data disc. AVI to DVD-Video is processor intensive and time consuming. If you're talking DLed AVIs, often the file is corrupt in some way. PC software players are very forgiving, but you'll find it's a different story when trying to convert to DVD. Variable bitrate MP3 audio, for instance, often produces an out-of-sync result. There are, of course, ways to correct such problems, for instance masking bad frames and decompressing the audio before conversion, etc, etc. But sometimes a file isn't worth the trouble, so be warned. Something to consider. Anyway, here goes:
Generally, freeware can do the job better, but not necessarily as easily. (Nero's encoding, for instance, is poor.) The sole exception is in choosing an MPEG encoder, the freeware ones are quite capable, but not user friendly, and much slower than professional encoders. So it may be worth it to pay for a decent encoder.
There are a number of free programs specifially designed for the task with novices in mind. One of the best is the old freeware DivX to DVD, which can convert a variety of formats (not just AVI) and is fairly fast. It can usually cope with VBR audio as well. There are almost no options at all, not necessarily a bad thing for novices though. Look for the free version on this page:
http://www.videohelp.com/tools?tool=vso_DivXtoDVD
There are more all-in-one converters on this page:
http://www.videohelp.com/tools?s=35#35
Freeware All-in-Ones, as a rule, bundle several open source programs together and automate the entire process for you, including authoring. No substandard proprietary crap. The Film Machine is pretty good, I'd recommend it as second choice. DVD2SVCD is quite good, giving the user a great deal of control. (Don't let the name confuse you). The learning curve is steeper, however.
It is worth one's time to consult some of the guides here:
http://www.videohelp.com
Go to "Convert" on the left, enter in the type of conversion, and read some guides.
Good luck.
