One of the questions that I'm asked the most is, "Can you make my computer faster?" On occasion there is a reasonable reason why someone's PC is running slow. Malware, adware, spyware, viruses, too many programs running at once – all those are things that can slow your computer down and they can be removed.
Unfortunately, this is usually the case:

There's a reason why people shoot a lame horse. There's a reason why old cars are on blocks in someone's driveway. Some things either can't or are too much trouble to be saved. And they'd certainly never be what they once were. It amazes me the amount of people that think that their 6 year old PC can be upgraded to meet the speed and performance of something they can buy in a store.
That's not what bothers me though. What bugs me is the response I get when I try to explain to them, logically, that it's probably time to upgrade. This is especially fun when you try to explain to upper management why your 400 MHZ 128MB web server isn't exactly cutting it anymore and why it's overloaded.
Upper Management: "We don't need a new web server, we have one on the books already."
IT Guy: "That's true. It was bought in 1998 and it's fully amortized as well as ancient. It needs to be rebooted everyday and the OS it's currently running has been end-of-lifed. The software has an expired license, which doesn't matter because the company that made the software isn't in business any longer"
Upper Management: "We don't need any unnecessary expenses"
IT Guy: "Hey, you know those emails you send me when someone contacts you about our website being down? Or the 3 motherborads you've had to buy in the last few years? Or the hard drives that have been replaced? Or how I need to reboot it at regular intervals, you know, just because it freezes up? Well, a new server would fix that."
Upper Management: "We don't need any unnecessary expenses."*
*Actual conversation
Really, I wish I did have some magic pixie dust or PC holy water that made your Pentium I or Macintosh Plus super fast, it'd save me a ton of headaches. But come on, even overworked stressed out IT guys have their limits.