As i type this i feel this is a stupid question but one I have to ask. How different are RPMs written for Mandrake say to thos written for RedHat?

RPM is Red Hat Package Manager. I assume RPM's for Mandrake would work on Red Hat and vice versa.
Its essentially the same OS , just slightly different distros with different packages included.
RPM checks dependancies so anything you are missing for that app you are told so you can hunt them down, either on the net or the distro CD's.

Hope this helps.

I remember reading on the Mandrake site that RedHat RPMs are 100% compatible with Mandrake.

Although I can no longer find that quote.

That is no longer the case. Back when Mandrake was just Red Hat with KDE that was true, but no longer.

The way RPMs differ is really complicated. Basically the problems fall into:

* Metadata differences. ie, redhat calls a piece of software one thing, Mandrake calls it something else, causing a false dep resolution failure

* glibc requirements - this is what causes problems if you install an RPM built for a newer version of your distro on an older version.

* RPM macros, mandrake and red hat use different commands to RPM sometimes

* File locations, ie Mandrake/Red Hat have different menu systems at the moment, though this is being standardised, so an RPM built for one distro won't integrate with the menu properly....

there are lots of details like that - basically stick to RPMs built for your specific version of your distro.

Thanks mhearn

Also what is the difference between a *.src.rpm and a i586.rpm?

src as part of the file name usually refers to sourcecode and i586 is to do with the processor type of the computer, in that case i586, I believe, refers to intel CPU's.
I think that also covers AMD and other compatible CPU's but I'm not too sure, I have seen Athlon-specific files before.

Which is better to download?

You want the binaries (so i386/i586/i686)

Thanks again mike