# Click the Browse button in the upper right-corner so the Panes are viewable at the top.
# Select an Artist in the pane at the top that you want to exclude from the iPod.
# Hold down the <cntrl> key and click the first checkbox--all the checkboxes for that artist will become unchecked.
# Continue for each Artist that you want to exclude. You can if you wish, as an alternative, select an Album or Albums and deselect that way as well
# When done excluding all the artists, click on File>New Smart Playlist
# Uncheck the "Match Any of the Following Conditions" checkbox
# Check the "Limit To" checkbox, set it to 100 GB, sort by Artist
You're done, now click on the iPod Options button in the lower right-hand corner and select this Playlist to sync w/the iPod (and any others
You can of course use the setting in the iPod options to only match checked songs, but I like creating the Smart Playlist because it allows me to easily see the size of the tunes I have checked. I've yet to find an easy "view" in iTunes other than this to see checked tunes.