Usually the name of jdk package shows the minimum machine architecture it
supports (e.g. i386, i586, 64b etc). You should use a jdk ending up with
i386 (i guess there is no i486 since their architecture is mostly just a
dual i386).

Sun offers jdk 1.4 for both i386 and i586(PII). If you wanna get further,
download the jdk source and compile it for preferred architecture.