I know that I can install an update to InDesign without losing the older versions (I currently have CS2 and CS3 on one of my PCs), but I want to know if this works with different language versions.
Nope, it doesn't. Sigh.
But if I add a later version (CS5.5) of the English, will it damage any of the needed Japanese files for the ealrier versions? The Japanese version has features needed for Japanese typesetting that the English versions do not have and cannot duplicated, which is why I want to be sure to keep it. On the other hand, I do not want to buy the Japense version of CS5.5 at this time but only tne English version.
Yes, installing English 5.5 on top of Japanese CS2 will most likely ruin your Japanese install. You really only have two options, here. I use both, they both work pretty well. You can virtualize an OS - for example I can run Japanese ID on WinXP in Parallells on MacOS, or I can run Middle East edition of CS2 in WinXP "XP Mode" on my Windows 7 machine. It's a little bit like the old trick of having a dual-boot or triple-boot machine for multilingual work, but you can just alt-tab over into another OS instead of needing to reboot completely.
The other option (that I can't seem to stop posting about ) is to ditch the Japanese CS2 and just go out and buy World Tools Pro from in-tools.com. That way you can more-or-less do Japanese typesetting in English ID. However, not every single feature of Japanese ID is implemented in World Tools, so check it carefully before you buy, in case something you rely on was not implemented. But I use it on a daily basis, and it's great.
Joel, do you say this based on some experience? It's counter to everything I've read, whcih has said you CAN install multiple localizations on the same computer, AS LONG AS they are not the same version number.
Based on just a little bit of experience; just one install, really. I'd obviously not read this stuff as closely as you - I just sat down at the malfunctioning workstation, clicked around for a moment, and said "Pull everything and reinstall only English stuff, put the Japanese install on another partition." So it could have been an unrelated problem fixed by uninstall/reinstall, I suppose. JWH, take note - I might be <gasp> incorrect on this matter.
Well, I've never done it at all, so I'm only going by what I've read.
I believe the dependency management improved substantially with [or after] CS3. So experience with CS2 is probably not a good indicator of what happens now.
I also suspect if you are willing to play tricks with mountable volumes and symlinks, or whatever the Windows equivalent is [err], you can probably get it to work, with pain and arcane tricks.