Ooh! Ooh! I get to use my “thoughtless janitor” analogy.
Picture working in an office, in one small corner of a large warehouse in which shelf after shelf of old-fashioned paper file folders are kept. In your office is a desk. Here are the parameters of your workday:
[ul][li]Your work consists of updating the records that are stored in the warehouse. The very first file folder (containing the index of all the others) is stored on the first shelf outside your office.[/li][li]You can only do actual work while sitting at your desk. This means anytime you get a file folder from the warehouse, you’ll have to carry it back to your office to work on it.[/li][li]The number of file folders you can have open at any one time (because updating one file often requires getting information from other files) is limited by the size of your desk.[/ul][/li]
The process of getting work done involves the following:
[ul][li]Looking at your to-do list, which tells you which files have to be updated.[/li][li]Going to the index folder to find the location of the files you need to update.[/li][li]Going to those files and bringing them back to your desk.[/li][li]Making the necessary changes (this process is actually very fast and easy - much more so than retreiving the files in the first place).[/li][li]Putting the updates files back in place[/li][li]Updating the index file (some files may no longer be necessary, some may have grown or shrunk in size, or been moved to other locations, etc.)[/ul][/li]
The key element, though, is that if you leave any open files on your desk overnight, the thoughtless janitor will toss them all into the garbage as part of his clean-up routine. In fact, the janitor is just waiting for the lights to go out so he can get in there and start his indiscriminate cleaning so he can go home as soon as possible.
Thus, you have the major components of a computer storage system:
[ul][li]The Central Processing Unit (CPU), the “brains” of the operation. You, in other words.[/li][li]The storage unit (a hard drive, floppy drive, CD-ROM), a permanent or semi-permanent place for records to be kept. This is your “warehouse”, which can be arbitrarily large.[/li][li]The main memory, the place where files are kept while they are being processed.[/li][li]The file allocation table, the main index describing where all files are kept (I know non-Win9X systems don’t use this name, but bear with me)[/ul][/li]
In practice, having a large “desk” means you can have more files open (or very large files, which would be the case if you were editing video, for example). There are diminishing returns, though, and doubling the size of your desk does not necessarily mean you can work twice as fast. Ideally, you get as large a desk as you need, plus a little extra, but not more.
Having a large “warehouse” is always desirable, and you should always get the largest hard drive you can afford (within reason; don’t sell the farm to get a humungous hard drive that you’re going to chuck in two years as obsolete, for example). Hard drives often have their “access times” listed in milliseconds (in effect, how long does it take to get a file from the warehouse), but these can be subject to exageration or resulted from ideal testing conditions, etc. If you care enough to start looking for specific manufacturers and models, I suggest you go to a website like Tom’s Hardware Guide and look at their test results.
In practice, organizing the files on your hard-drive can have a much greater effect than choosing the model. It’s important to delete older unwanted files and “defragment” the rest.
As for the janitor, think of what happens when you have a sudden power failure or comptuer crash or other interruption. Whatever you were working on at that moment is lost. All you have are the files safely stored on your hard drive, hence the need to save your work frequently if the information is critical or your computer/eletricity is unreliable.