If I restore my system using Windows restore to a point prior to implementing Truecrypt total disk encryption, will Windows 7 fail to boot due to the fact that the Truecrypt drivers are no longer installed in the prior restore point?
I'd expect problems (and wouldn't do that). It's likely that it could happen, do you have any need to do such a restore?
Now, I'd never recommend system restore. It happened to me that I had files that it deleted, sometimes I didn't knew what it was doing, and others, it didn't restore what it should. If you can, move your data to a separate drive/partition, periodically make backups (especially of your most important data), and reformat your windows partition once in a while, better yet, keep a system image ready to recover from.
But if you insist, make a drive image, try to do the restore, and if it fails, restore it.