Is it possible to install and run Linux programs on Mac OS X Leopard 10.5?
What program are you after in specific? It is probably available from Fink.
VMWare Fusion is pretty cheap if you are a student, I think paid about 40.00 or so. It will also let your run Leopard server as well . . . The Sun offering, Virtual Box, is free for students, but I've had problems with it doing filter driver development (I Do all my PC development my iMAC via VMware fusion). If you are doing non-driver development, then I'd go with virtual box . . .
You can't run native Linux apps on OS X; however, you can usually recompile them to run on Mac without too many issues. You'll need to have X11.app installed (this used to not get installed, but may be with 10.6).