I hate you.
you can use Hammer 4, I can't.
I tried for one month to install and use Hammer 4 on my comp : no way, it's an endless and very tiring fest of reboots, "no more available memory", slowdows, freeze and blues screens ...
damnit I am so frustrated, I had so much ideas of maps and mods with Source ... omg fuck you have fun building great stuff with Source ...