Yes. There is a lot of 1-3yr hardware being dump for "green" boxes. Many boxes run Sun or Linux os's. Have not tried vegas, but I have many 3d apps setup fir renderfarms that work fine. I sometimes will divide up projects into smaller jobs to ease overhead. I also have multi copies of lib's of the most common functions, filters, media spread thru-out the servers to managed bandwidth demands.
No reason why they shouldn't work. You can install Windows on them if you want to.
Beware that most of them are built for reliability, not efficiency. Not that reliability is a bad thing at all, but they do tend to be huge power hogs. That may be one of the big reasons they're being dumped so cheap. Fortunately our 5 racks are all at places where we pay flat fees rather than by the kilowatt.