First you spend more for having a Mac. Then you have to reinvest you money into software which you can no longer use on your mac.
My suggestion is getting something custom built.
Here's a company:
http://www.maincomp.com/shop/showcasep
http://www.compubuzz.com
http://www.newegg.com
I've bought from compubuzz and newegg before.
Depending on if you need a monitor or not. YOu could probably spend about 700-900 without monitor to satisfy your needs.
My suggestions are:
512mb Ram minimum
1GHz+ CPU
Windows XP or 2000 professional.
80+ 7200RPM Gig Hard drive. DVDs are big the more space the better, Faster that space is the better.
DVD-R drive.
You may elect to purchase sonic dvd it.
Or Pinnical Studio DVD software.
you may also visit
http://www.vcdhelp.com
to see how they convert Video to DVD, and other digital formats.
Yes some things they talk about are of questionable legality. But the techniques they use are very good for legit reasons such as yours.
Pinnical sells probably the easiest to use software. Which is also rather powerful.
Well good luck.


