Well,
http://bssc.sel.sony.com/Professional/markets/sound/vegas_rebate.html
If you do the math, the upgrade is $510 (Vegas) and $750 (Vegas + DVD)
If you buy Vegas 4, between March 1st and April 30th, they give you a $50 rebate. If you buy within that time, you get a free upgrade to Vegas 5...
I would assume the upgrade price for current owners would be less, but for now, you are guaranteed the upgrade for $50 less than what it costs for Vegas 4 now.
This is a great deal for the people who have not bought Vegas yet. You know the price is going up. So you can get Vegas 5 for $50 less than what I paid for Vegas 4. Damn!
Al