I suggest you upgrade to Vegas Platinum 10 if you are going to move to Windows 7. Vegas 8 was never tested in Win7, so it's expected to be crashy, even if at first glance might seem "ok". It won't be in the long run.

Ubuntu will NOT support Vegas. Ubuntu Linux requires its own applications, not Windows ones. There are emulation and runtime techniques to run simple Windows apps on Linux, but they are very slow, and even more crashy.