When you boot your new kernel for the first time, you should take a careful look at the kernel diagnostic messages to make sure that all of your hardware shows up and that the drivers are doing what they are supposed to do. Unfortunately, kernel messages tend to fly by so quickly that you can't see them. You can run dmesg to see the most recent messages, but to see everything, you need to look at your log files.
Most /etc/syslog.conf files send kernel messages to a file such as /var/log/kernel.log. If you don't see it anywhere, add a line like this to your /etc/syslog.conf:
Then run this command:
kill -HUP '/var/run/syslogd.pid'
You may wish to make a checklist for your new kernel to make sure that your system still operates as it should. Here's an example:
Do the network interface and network firewalls work?
Are all of your disk partitions still visible?
Does the kernel see your serial, parallel, and USB ports?
Does all of your external hardware work?
Does the X Window System work?