If you're still running "Lucid", 10.04, and are having driver problems or something, there are now 3 different newer kernels available.
The kernel contains wifi drivers and so on. The only main class of driver it doesn't contain are graphics drivers for X.org - X contains its own. However, some newer proprietary graphics drivers, e.g. from nVidia, may require a newer kernel than Lucid's 2.6.32 to install and work correctly. These kernels are thus a considerable boon for quite a lot of reasons and may help 10.04 to remain useful for some time to come yet. For instance, they are great if you don't like Unity and are waiting for GNOME Shell to become a bit more mature, say. They aren't just for servers.
They newer kernels are backported from 10.10 ("Maverick"), 11.04 ("Natty") and 11.10 ("Oneiric").
There are 3 different kernels in each family: one generic, one generic with PAE support for 32-bit machines with 4GB or more of RAM, and one for servers.
If you look in Synaptic (or the package manager of your choice), you should see (for example):
and the matching linux-image-generic-pae-backport-natty and linux-image-server-backport-natty.
There are also families ending -oneiric and -maverick.
From memory, the standard 10.04 kernel is version 2.6.32-xx where -xx is the current build.
The Maverick series are 2.6.35-xx, Natty ones are 2.6.38-xx and the Oneiric series are 3.0.0-xx.
If you install (say) linux-image-generic-lts-backport-natty, you will get the current build of 2.6.38-xx and it will be updated as newer builds are sent out. You don't need to install a specific version - if you do so, it will *not* be updated.
I have found that the PAE kernel will not boot on some Celeron machines which have the PAE functionality disabled, so I recommend against using it unless you know you will need support for >= 4GB RAM.
I have resolved quite a few problems with these, including machines that hang on shutdown rather than switch off, getting newer WLAN chipsets going that did not work with the standard 10.04 kernel, and supporting some Sony Vaio machines that will not boot older kernels successfully.
The same kernels are also available in Mint 9, as it is based on Ubuntu 10.04.