Until fairly recently my primary desktop was a 500Mhz P-III w/ 256MB and two disks, 9G and 11G. Sure, I had to turn off the desktop effects. But as long as I stayed away from whizzy graphical stuff it worked fine.
I still have it hooked up headless. I can run a full LAMP stack (Linux Apache mySQL PHP) and it never breaks a sweat. I did Java development on it when I was teaching myself.
You may have your reasons for not learning Java, but your current hardware isn't one of them.