I want to use the RPMs on qmailtoaster to manage my mail server since I really don't have enough time/experience to manage all of the required services. I want to move to a Debian based server from RH 7.3 so I can apt-get for security. Is this a good idea? I know I can install RPM on Debian, but is it a good move? Maybe I should use Fedora? How is security going to work on Fedora though? This is going to be for personal websites and email.

There may be a couple of options for you which naturally depends on your time and fund$.
For example you want to use RPM's on Qmailtoaster without having to deal with the headaches. You could sign up with a managed server provider to take care of this, OR you can ditch the easy way and compile it straight frm source :)
Apt-get is good for at least getting some of the packages, but it never hurts to build your own *.deb packages set a directory to your own built *.deb packages and edit your sources.list file to point to your directory that will contain your *.deb files, and run apt-get and you will have the latest updates.
Naturally you will need to get the experience to admin your own linux box, and then back up your config. If you don't have time you will need to make the time for it.
I think Debian is a great distro and have used both RH 5.1,6.0,7.3 & Debian potatoe->woody, and I prefer Debian for it's no frills approach, simplicity, and easy to use and install distro.
However test out the RPM's on your Debian box first you can always convert RMP's to *.deb packages via Alien. So after converting your rpm's give it a shot and try to install them top see what happens.
Do you have your own server at home where you can practice and sharpen up your admin skills?
I hope this information was useful.
-Bones

Yea, looks like I'm going to convert to .debs, I didn't know that was an option.

Thanks for the heads up. I am a pretty compentent admin, I just don't want to spend all day worrying about my server. I have 2 years experience running RH 7.3 servers and am now looking to make the transition.

The reason I want to use the RPMs from their site is they're pre-configured to work together. I know I could get all the packages separate and get them all working independently, but this way I run the RPMs and then I have a completed mail server thats already configured for me.

Oh well that's cool. Since they are already preconfigured then that would make the work a bit easier, but have you decided which distro to use?
-bones

Still throwing them around, sometimes I'd like to try slack etc, this server is mostly going to be LAMP with Ventrilo on it.