Two versions of one program?

['TDK' Tim Kearn]

List,
Updated Safari and Java from the Software update. Mt wife now has 
trouble accessing her work 'intranet' site from home. It was fine when 
she was using the previous of each.
My question is - when she logs into the iBook (clamshell) can she use 
the previous versions while the rest of us (family) use the current 
versions in our own accounts? Hoping thats it.
Using 10.6

TIA,
Tim