There are lots of utilities to show total ram/used ram/swap. I have memwatch here (should be on Hobbes along with many others)
Ramfs dynamically grows and shrinks and uses swappable memory so will swap out if it grows bigger then available memory. It has some quirks, generally only shows 64MBs free and can give out of space errors for large files. Also doesn't work right for LIBC symlinks.
It's easy to test.