Buying a computer is like buying a car or anything else, and is very subjective to people's opinions, and afterwards, very subjective to how they maintain them. There are lemons. There are perfectly fine computers that will run for 10 years. You expect it to be junk it will be junk. You take good care of it and it will probably run well for years. Maintenance is key. Especially if your house is hot and/or you have a lot of dust. Parts that you have to watch out for is the HD, CPU, GPU, and power supply. Mobo's, ram, etc. can go bad, but not nearly as often as the other parts.
Laptops:
The quality of laptops goes up and down with each company in different years. Some of it has nothing to do with the computer manufacturer and everything to do with the OEM parts or design. If nvidia gpu's run too hot, there's not a lot dell or any other company can do when computers start burning out 6 months to a few years later. They try to follow the tolerances set by AMD, Intel, nvdia, etc., but sometimes that's not enough.
Lately HP has had really good deals (in the states) on laptops with video cards (lower to mid range gaming machines). Mixed reports on them, but great bang for the buck when on sale. I'd generally only buy a budget laptop from dell, but people do like their gaming laptops. We've had a few different ones and a couple of higher end with discrete video. The problem with people saying they had problems with any laptop is how did they take care of them? Was there a design flaw? Bad parts/lemon?
Chances are they died of heat and that's usually from dust getting into them or them not being used correctly. Using it on your bed with the exhaust closed off is bad and will overheat your cpu and eventually kill it. Dropping them is pretty bad too. Especially when it's on.

So I take everyone's claimed experiences with a grain of salt. My friends was overheating a bunch and it turned out he some virus that was trying to do all this crap all the time. Bloatware doesn't help either. Solid state hard drives helps a bit with abuse, heat, and very slightly with less power consumption. SSDs are well worth the investment for a lot of people who don't need 250+ gigs in their laptop, but not if you are trying to get the most bang for your buck.
Desktops:
Desktops are obviously not as fragile simply because they are almost never moved (while on) and can handle the heat much better. They still need to be cleaned out depending on how much dust is in your house and it's not a good idea to drop them either.
The op asked if he should update/upgrade the parts on his computer. The answer is no for many reasons.
Next is what options he has. He said desktop would work.
What desktop. I say to keep checking the deals site and wait for what is considered a smoking deal and in your budget. Try to get an i5 or better machine with 4+ gigs of ram. Then just add the bare minimum upgrades as they go on sale. Check to make sure the power supply can handle any upgrades you plan to install. Buy it with Amex or any credit card that offers extended warranties when possible. Take good care of it. Add a fan if the interior of case if the video card you buy or comes with it seems to run hot.