You need gcc version 2.0 or later to compile gforth.
configure has the following useful parameters:
-direct-threaded: setup for a direct threaded interpreter; this is faster
on many machines, but needs special support. Unsupported machines will
ingore this switch. On some CISC machines, direct threading isn't an
advantage over indirect threading.
-without-debug: omits the -g switch and creates smaller images on machines
where "strip" has problems with gcc style debugging informations.
--help: tells you about other parameters.
If your make has trouble with the Makefile, "make gforth" might work.
If your installed gcc isn't called "gcc" (eg. called "gcc-2.6.1"), type
make CC=<whatever you call your gcc>