First things first: never spend something that you don't believe you can pay off in the future, that's the best general spending advice I could deliver to you, and I've been living happily like that for a good long time. While the thought of a high-end computer system is just so incredible, the $5,000 price tag should be plenty of a turn-off to your technology temptations. We're trying to make sound choices for what your wallet can afford, not what you wish you could afford.

So, computers. There are two things that I can speak on about going the cheap way with those. First, if you're buying a computer, don't buy more than what you need. I've seen fellow techies buy notebooks or desktops with very capable hardware components ranging in the price ranges of $200-$500, but then they waste all of their power and value in playing addictive flash games online like Desktop Defense or Flash Flash Revolution! That's like a keeping the Porsche in the garage on a sunny day, it makes no sense!
If you were to buy a new computer, I only recommend that you get at least a dual-core processor and 1GB of memory. If you're not looking for 3D-gaming or anything of that sort, a dedicated/separate video card is entirely pointless. Integrated graphics processors are enough for your day to day uses.

The second big thing I could say about smart spending on computers is about troubleshooting issues or problems you might be having. Every computer has its day, every computer has a moment of brilliance, speed, and genius... and then again, every computer will have it's moment where you should just take it back around the shed and do the “Old Yeller” on it. Being the tech-guy that many friends and most of my family know pretty well, I've personally wished and argued for the deaths of many systems. I'm sorry Jason, but a 533MHz Celeron and 256MB of memory is just not right for your XP machine and the way you use it.
And stop downloading midget porn and hiding it in the Windows System folder, that stuff is not cool at 9AM over some breakfast debugging.

There are problems that could easily be fixed at little cost to you, and I think one of the best solutions is even free! First off, if you're machine is new enough to use the DDR2 type of memory, then memory problems are easily fixable and the prices of DDR2 memory are just incredible right now: I just bought 4GB for less than $60 earlier this month, and that's worth every penny. If the motherboard, hard-drive, or pretty much any other piece of hardware is giving you problems, then I'd consider what kind of machine I'd be extending the life of by replacing the part. If it's a slow, single-core Celeron with slow and old memory sticks, or just a poor performer in general, I'd consider shopping around for a new computer.

Now, if you're experiencing issues with software, then that's a totally different thread of advice. If this is your first time having a problem with Windows Vista, XP, or such, then you have a number of options to address the issue. First, try to remember your system backup software that's included with these OS', it's usually found in the memory directory by All Programs > Accessories > System Tools > “System Restore”, or something close to that. Use that software to backup your system when it's in working condition, then if you experience a problem, restore the system to that backup point in an attempt to address the issue.
If that doesn't work for you, I'd suggest using your OS' physical CD/DVD, popping that in the drive, restarting the machine to boot from the disc, and looking for a 'repair' option that's usually included with these discs. That should address the problem, too.

If you're consistently having problems with Vista or XP, then I suggest using a different, safer, and cleaner operating system: Ubuntu, or some other user-friendly form of Linux. Linux has been making some huge leaps in ease-of-use and capability these past couple of years, and Ubuntu is a prime example of their progress. These free operating systems also run beautifully well with older, slower computer systems that are bogged down under the resource loads when using Vista or even XP. The transition from Windows to Ubuntu is becoming easier with each release, too, and there are plenty of guides and friendly tech users that'll take the time to chat or email you with help in making the jump from Windows to Linux. Some distributions of Linux even come as LiveCD versions, which don't install the OS on your computer at all, but still gives you the chance to try out Linux with no consequence. So if you're system is constantly slow, or you're just tired of problems in Windows, give Linux a try before buying an overly-expensive Apple machine.