SQL server 2005 does not need VS2005,
If the SQL server is just a database server than there is no need for visual studios on the server as its not going to be running any winform or webform. The only thing that it would require would be when its installed on the server when it checks through... You might have the possibility of removing vs2005 that contains a file that SQL server is now dependant on.
as an example, I install SQL server 2005 that contains .net 2.5 but I then go on to install VS2005 that also has .net 2.5, I now want to uninstall VS2005 that also uninstalls .net 2.5 rendering sql unable to work....
I just gave that as an example ;) its not true but there could be a file but I would presume that when uninstalling vs2005 you would be informed about dependency on other application. VS2005 in my opinion should not be on the sql server and should only be if that on the dev server for development/testing but in my case I don't even have that, I have vs2010 shell (cut down version) that is installed with other apps.
VS2010 would only be on my VPC and/or my host pc only so in your case it should be the same as its an sql server and you should need the space at some point in time where its just not needed at all!