If you don't want to dedicate some hard disk space to a unix installation, you can try a live linux cd, like
Damn Small Linux. Its a 50MB download, you can burn it to a cd and use it directly, without installing. It uses tcc (tiny C compiler), but if you want a full fledged compiler like gcc, you can get it from the MyDSL extensions for DSL.
Also, if you have some amount of free disk space (200MB or more), you can try these linux distro's which can run directly off a FAT32 partition, ZipSlack is an example.