Defragging a hard disk once a week (or especiallly once a day!!!) is *far* too often. When defragging, the machine reads and re-writes data on the disc in order to more efficiently order it. While it's true there is a definite advantage to keeping fragmentation down, there's a point of diminishing return. There's almost no benefit from doing it more than once every month (or even every few months) that isn't *far* outweighed by the risks.
One exception might be a person who is constantly installing and uninstalling stuff (say, someone like myself, who works with lots of different stuff on a certain machine; evaluating different programs, utilities, drivers, etc). But, if you just install stuff once and leave it, a drive *won't* become fragmented for quite a long time in normal usage. Disks become fragmented - over time - by filling space left empty after previous deletions is filled in with new stuff (where the 'new stuff' outsizes space left for a single unit of 'ex-stuff', but will fit over the collective space abandoned by several 'ex-stuff' units). New machines hardly ever get fragmented just from adding stuff, especially with big hard disks - until you start deleting/adding/deleting/adding...
Cleaning: The canned air works, for sure - but I usually recommend against it, and I'll tell you why: You can darn well blow something into (or worse, under) a place it shouldn't go and cause a problem. For one thing, some PC fans aren't sealed well at all on the back side, and I've seen several instances where dust, blown forcibly off a heat sink (without first removing the attached fan) caused the dust to blow inside the back of the fan and cause the fan to become noisy. Left untended, this fan will fail much sooner.
Yes, the dust needs to go - use a vacuum; that way everything is coming *out*, not being flung all over inside the case. They make inexpensive, static-safe micro-vacuums just for this purpose. I personally use a regular full-sized vaccum with a small, static-safe nozzle and brush to loosen dust. All the cards should be removed and fans removed where possible from heat sinks - allowing the heat sink to be cleaned of dust without it getting inside the fan bearings (as above). If it's done often enough, there's not usually enough build-up to warrant tearing things apart for this - but then again, most people let it go far too long. It should be done once a month.
Oh, and the term "CPU" also applies to the chassis itelf, not just the processor. Most of us who've been around PC's for a long time use the terms interchangably; in fact, you'll seldom hear us refer to the CPU (chassis) as the "tower", which seems to be the trend these days. Most people I work around say "CPU" to mean the chassis, and "processor" to mean the...well, the processor :costumes:
And before anyone gets all whacked out of shape at me for disagreeing with the 'resident guru(s)' or whatever - I lurk here regularly and I've seen it happen. All stated opinions in my post are my own $.02., based on my own (27-year) background with computers and electronics. Your mileage may vary; this is America. You are free to act in as ill-advised a manner as your pocketbook and free time will permit.
