I made the mistake of installing gawk and coreutils without prefix=/tools

I redid the installs properly but I have to assume that these packages were installed to my currently running system, right? This wont cause some weird errors/compatability problems for my current system will it? (Just out to reveal my total ignorance)

I assume that it wont. I guess I will find out.

My guess is that they will be installed into their default locations, which is probably in /usr/local, /usr/local/lib, /usr/local/bin and so on. If you don't notice any change in the way your system is behaving they probably aren't doing any harm as your system tools are probably installed in /usr (/usr/bin, /usr/lib and so on) and if your $PATH looks in /usr/bin before /usr/local/bin you should be OK. You could try and look for the files and delete them. I started from Mandrake which is dead easy to reinstall so I've no fear of trashing it.

If you forgot the prefix they would have gone to /usr/local, so no harm no foul.

If you happened to have installed them into /usr the tools would still work, however once you remove /tools from your host they will break ( they will use /tools/lib/ld-linux.so.2 as the runtime linker )