Multiple jquery codes interrupting each other (help)

I'm working on a site which has a jquery drop down menu and a left column with sliding tabs.

One has jquery-1.2.3.min.js and the other jquery-1.3.2.min.js but when I have both at the same time, the drop down stops working and vice versa.

What is the best way to have multiple jquery scripts/codes without one interrupting the other one from working properly?

Use jQuery.noConflict(); would probably work, also why can't you just use one of them. It's probably easier to just slightly change the old script to use 1.3.2 if it doesnt work already. That way the user only loads 1 js file not 2 which will speed up your site and 1.3.2 is alot faster than 1.2.3. It would only take abit of debugging to check if it worked using something like firebug and replace a function maybe with the updated equivalent.