There are generally few issues in having both VS2005 and VS2003 installed on
the same machine. Most of the issues you will run into is at times a project
you want to be opened in 03 will be taken over by 05.
As for where to get it, if you are an MSDN subscriber you can download it
directly from Microsoft, otherwise you can order a copy of Beta 2 from
Microsoft over at
http://lab.msdn.microsoft.com/vs2005/get/default.aspx
I do not know of any expiration dates, however it should be noted that the
final version is just a month away from release and there will no doubt be
enough changed between Beta 2 and then making things built with Beta 2 not
optimal for the final 2.0 framework.
Due to licensing restrictions you are not normally able to use this beta
software for production use (ie build an application and sell it or provide
it for day to day use by others), a little exception created by Microsoft is
a Go-Live license that allows you to start using it for more things than
normal immediately. You can find more information on this over on
http://lab.msdn.microsoft.com/vs2005/golive/default.aspx
Brendan