I've been getting a few e-mails from people asking where they can download MSE now that Microsoft have closed off the beta. The short answer is I don't know.
I can tell you the MD5 and SHA-1 hashes, so you can at least make sure you can get a copy that hasn't been tampered with if you're that keen on using it.
There's three installers:
mssefullinstall-amd64fre-en-us-vista.exe (3.72MB) which is the installer for Windows Vista and Windows 7 64-bit, its hashes are as follows:
mssefullinstall-x86fre-en-us-vista.exe (4.72MB) is the installer for Windows Vista and Windows 7 32-bit.
mssefullinstall-x86fre-en-us-xp.exe (7.51MB) is the installer for Windows XP 32-bit.
So if you are going to go to any lengths to get hold of it, at least get one which hasn't been modified to include any unwanted surprises.