Here's an easy way to verify a sha1 checksum in Windows, assuming you have Cygwin installed:
echo "60ab4099e811d79fe90ae8d8f184b163bdc57fa8 TortoiseGit-1.7.6.0-64bit.msi" | sha1sum -c -
You can use the "Bash here" Explore menu to open a Cygwin Bash shell in the directory containing the file. There are also other commands, such as 'md5sum' and 'sha256sum'. As always, RTFM for more details.
Now, I can verify my checksums for the sake of it.