Running software from external disk.

1) If it is connected to your laptop all the time, you probably will not have issues. But once you disconnect it, the system may become unstable if it has open files/programs running off of the drive.

2) There are some programs that run independant of the registry. Those would work in this situation. But MS Office for example would not work because it relies heavily on the registry (plus it would be a licensing violation ;0 )

3) Yep, but don't depend on stablility if these programs modify the registry to work. If they add any services that point to the drive you may even blue screen the machine.

All in all, I would not recommend sharing a drive like that if you are going to be installing software on it. Use software designed to be portable (I think firefox is comming out with a version.)

Also remember that most licensing agreements only permit you to install the software on one computer. Not one hard drive and share it.

tx cm5400.

The programs I have in mind are more like little freeware/shareware or opensource so there won't be any license problems.

Now that it's said. If it's not possible with programs that need registery "access", how can I check if a program needs it or not. (Beyond the ones that are just zip packages like eclipse).

Or is there no possibilities to mirror the register to the drive to make it work?

If a program runs without installation (just unpacking it to a separate folder allows you to run it sans problems), then there is no issue with registry. Otherwise, you'll have to make a registry snapshot before you run the install, then another right after that, and compare the two. I cannot quote the snapshot-making program names off the top of my head, but they exist in great numbers (and some of them are free). Try at Winternals / Sysinternals, that's always a good place to start.
Or you can do it the hard way, install things on the external HD anyway, then unplug it, carry it bodily to another box, and try running the app in question from there. If it runs, then you know that it either does not make changes to the registry, or even if it does, it doesn't really need them. If it doesn't run... tough.
If you go for the "install anyway" option, I'd suggest doing it on a test box. A word to the wise: even your usual computer can make a test box in a pinch if you have disk imaging software (Acronis True Image, Symantec Ghost...).

Now, for the installation on other laptops: everything depends on those registry changes. If a program runs without being installed first, then all you have to do is copy the program's folder to the target box and voila, you're set.

Hope this helps :-)

Tx but what I really want to know is how I can find out if the changes made are needed to run the program.
I know how to find out the changes in the registery but the question is: Are those needed to run the program?
Most of the keys are usually for uninstalling or licensing but there are many keys I don't know. So how to find out?

that's why I suggested a test box - even if it does break, you can restore the image (some 15 minutes, tops).
As for destabilizing your computer: as long as the soft in question is something you'd use if it was installed to your internal HD, no problem; just see to it that the program is not running when you're disconnecting the drive.
If you're afraid of breaking other computers, well, if the program runs, there should be no problems, and if it doesn't, even less.
At the end of the day, you can rephrase the question and seek answers to THAT. The question would be: Here's a list of software. Can you tell me which of these absolutely must be installed, and which just have to have all their libs at hand?
Not to patronize you or anything, but why do you think you have to test everything on yourself? Ask around, people should have tried this before you. If 3 people tell me that running, say, IrfanView from a copied directory (no install) works for them, then I assume it'll work for me as well.
And now, have a good WE. Bye!

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