I want to upgrade my packages to newer versions but my server is still on lenny. I've read a bit that lenny-backports may come in help here. Could you please tell me what to do to upgrade to lenny-backports and if it can harm in any way the current packages and server overall? I just got really scared from reading upgrade notes for squeeze that I thought I would rather first try backports for safety.. hehe.
To "upgrade" (it's not really an upgrade, merely an augmentation) to use lenny-backports, follow the instructions at http://backports-master.debian.org/Instructions/ (it's targetted at squeeze, but replace 'squeeze' with 'lenny' and it'll all work nicely).
You really should at least start planning an upgrade to squeeze; lenny's security support won't last forever, and you'll likely find that plenty of things you want to upgrade haven't been backported.
Firstly, don't get scared by the upgrade notes. As usual, the Debian guys are very thorough and cover every conceivable angle. If you read the stuff carefully, you'll realize that most if it won't apply to you. But it IS a good idea to follow the general process. I have upgraded quite a few of our machines to squeeze (servers and desktops) and never had a problem with the basics.
However, if you want to try lenny-backports, that's not a problem either. Simply add the repositories to /etc/apt/sources.list and run
apt-get update to retrieve the package information. Then decide which packages you want to have on the latest version and run
apt-get install <package> to install the latest version.
Details can be found here.
You shouldn't have any trouble with Lenny backports. It's an officially supported mechanism, now.
All of the packages have been built against the original distribution, so you won't hit any dependency snags (You may find it makes you move to the latest Lenny package for some supporting libraries, but that's about it)
The instructions cover adding the right lines to your
sources.list (I won't repeat them here.)
The only downsides are that only a small(ish) subset of common packages from the original distro will have a backport variant; and that the version you'll find there still might not be recent enough for you.
That said, the way you phrased your question suggests that you're just looking to do a general upgrade. The best advice I can give is to just stick with Lenny unless you specifically need a package variant that has some new feature you require. Lenny is still being supported, so you'll get all the security patches you need and you can take your time planning a move to squeeze.