Q Thinking back to my last transfer of data and documents from an old computer to my current one, I wonder if I can avoid all the hassle in future by not having anything to transfer, and simply plugging an external hard disk full of my software and documents into any new PC I use.

I have an external disk at the moment that holds my data so that I don’t have to keep inserting individual CDs. I also use it as backup by saving copies from the computer’s internal disk.

I envisaged having two external disks with one as a backup copy. Is it feasible to move everything other than the operating system to an external disk and what would be the minimum disk I would need inside the computer for it to work?
Alan Middlemass

A In theory, this is possible to a certain extent. The easiest way to make this work is to not go quite as far as you propose. Instead, install the operating system and the regular applications you require (such as a web browser, office programs and anything else you use regularly such as a photo editor, perhaps).

Now you have a clean operating system installation that you don’t need to touch. You can save all documents to the external hard disk, or a USB memory key, whichever is better for you.

As with all disks containing documents, you should make regular backups of this, which is also something you’ve considered. The only hassle may be convincing all the programs you use to save their documents to the external hard disk rather than the internal one they’re used to. Some programs will always default to saving to the C: drive whatever you try, but if you’re willing to put up with that it should work fine.

While it is technically possible to go a step further and install programs such as your office suite and web browser on the external disk, this may cause problems and, in any case, the point of the exercise is to allow you to switch computers in future without hassle.

Installing programs to an external hard disk will not generally accomplish this – when you plug it into another computer the programs will still seek information held on the old disk and may not work properly, if at all.

There are portable versions of some applications, though. You can install these on your external hard disk and they will work fine on any computer into which you plug the disk.

The only problem is that you’re limited to the applications available, but the list is getting longer and longer. You can find some free portable programs from Portableapps together with instructions on how to download. The list includes the Firefox web browser, an anti-virus program and Openoffice for word processing, spreadsheets and presentations.

If you are planning on working with very large files such as high-resolution photos or video, you may want to investigate a connection socket called eSata. This is an external version of the plug used inside the computer for hard disks and optical drives. It will provide better performance compared to using USB.

Some external hard disk enclosures such as the AC Ryan HD50114 come with this socket but you will also need to find one on the computer, or install a Sata expansion card with an eSata socket.