Is it necessary JDK to execute a servlet??

[cadbilbao]

Hi!

I'm trying to carry out 5 servlets (they use XML).

By the moment and while developing, I'm using JDK 1.3 + Tomcat + Xerces, on Windows NT 4.0But I want to install it on other Windows PCs, and I wonder

if it is necessary to install JDK, or it's enough with JRE.

I would like also to know if there is another kind of Free Java Web Server, appart from Tomcat, or a system wasting less resources.

Thank you very much, and best regards.