For the new computer im going to buy Im thinking about using Linux as OS and use the money I save on better hardware. Im thinking about using Dynebolic installed on my HD as the distro to use since it seems to have the software I need. Im woundering if there are any negative sides to using a Live-CD installed on the HD opposed to a "normal" distro.
Im going to use the computer only for 3D graphics and videoediting.
sorry for my bad english...

No, a lot of people, even more as of late, are using Live-CD's to install Linux to their HD. It's a nice easy way to get through the install while having a full live computer during the install process (so you can google errors and such).

Personally, I wouldn't choose a distro based off "it comes with the software I need" because if it comes with a distro, there is a VERY good chance you can get it on any distro. I'd tend to look at how package management for installing other applications or upgrading/updating the distro.

Cool

Here are some drawbacks that I can think of:
1. CD size limitations may mean that there is a reduced number of included packages
2. RAM-disk based instead of HDD dir for tmp files (RAM is faster, but uses up memory that could be better allocated)
3. Configuration assumes no persistent settings from boot to boot
4. Generic rather than hardware specific support

That's not to say that most of these couldn't be changed once it's permanently installed on the HDD, but it's more trouble than going with a distribution that already assumes it'll have write access to certain files.