Some of the binaries may need to be reinstalled from the source directories; I had to do that with lilo, for example, since my version was newer than the one on the Slackware installation and I hadn't bothered to save the binary from /sbin. You'll want to check through your restored programs and confirm the existence and correctness of configuration files, libraries and so on. In some cases, you may have to restore things in a specific order; you did make notes during backup, didn't you? ;-)