Hello Angela
It will not affect anything on working on ACS server. The doc says that it should have minimum JRE version.
My suggestion will be that you should have atleast minimum version installed i.e. Sun JRE 1.4.2_04 and later upgrade to latest one. I have installed the latest java version in my lab and it is running fine.
Let me know if the above reply answered your queries.
thanks
Shree