some colleague of mine, his PC broke and apparently he has this unused but still operational pentium 3 sitting on the attic, so while waiting on the replacement, he would like to use the pentium 3. the eclipse doesn't have to be recent version, as long as he can code some java on it. thanks
The issue is more likely going to be with the operating system. A Pentium 3 with (what I guessing has) 256MB or so of RAM is not going to work with any of the mainstream distributions (especially if you intend on running a graphical interface). Also, current distributions would probably not support the hardware from the P3 era - the network controller, disk controller, video controller, etc. You will need to dig-around to find a lean distribution with driver support for the hardware you have.
Only way to know for sure is to fire it up yourself and see if it runs satisfactorily. Any response you get here is going to be at best an educated guess, at worse a wild stab in the dark. Unless you get really lucky and find a developer who has been too tight to buy new hardware inside this millennium. (Quite unlikely that last one)