VS2010 beta 2 is sloowwww on my machine. I'd like to start playing with .net 4 though. Can my vs 2008 solution's target .net 4 beta 2? How?
No, you can't target .NET 4.0 using VS 2008.
To speed up, you can try to create this key in Registry (worked for me):
[HKEY_CURRENT_USER\Software\Microsoft\Avalon.Graphics]
"DisableHWAcceleration"=dword:00000001
More info here Visual Studio 2010 Beta 2 editor performance fix running on a virtual machine and Graphics Rendering Registry Settings
No you can't you need at least visual studio 2010 to target .net 4.0
来源：https://stackoverflow.com/questions/1743525/can-i-and-how-do-i-target-net-4-with-vs-2008