I am in agreement with everyone else. It depends on the computer brand, model, specs vs the merchants name.
I never bought a laptop from Wal-mart, just a lower end cheap Desktop HP with Celeron 700Mhz processor 13 years ago to replace my $50 in mixed guts aged Pentium 75Mhz. I got 2 solid years of daily gaming out of the HP minitower from Walmart with no problems, then sold it to my brother inlaw for 50% of what I paid for it new and he is still using it oday with Windows Me. And then I upgraded to a Pentium 4 2.0 Ghz that I bought at Staples ( as an $799 open box unit that was returned that was for sale for $569 to move it out) in which I wasnt happy with that HP Pavilion full height tower because its motherboard was lacking an AGP slot, and thats probably why the orginal owner returned it as well because it couldnt run any good games without a video card upgrade and a video card upgrade using a PCI slot wasnt going to cut it. So I had to sell that within 6 months of owning it to a guy at work for about 75% of the price it cost me and buy a Compaq Presario with AMD Athlon XP 2800+ at Radio Shack for $549, in which I got permission from the Radio Shack clerk to open the side pannel on the floor model and look inside before buying one sealed in a box.
My laptops that I have bought new have been through Best Buy, Tiger Direct, and Newegg. When going in to buy a laptop at Best Buy when attacked by the geek squad patrol, I told them that I wasnt interested in the Acer that they were promoting, and was only going to buy Toshiba. Then the kid brought out the most expensive Toshiba they had that likely had the largest markup and I said I will tell you which one I want I dont need suggestions. I then selected a Toshiba Satellite AMD Dual-core for $429 with 17" display around black friday of 2009 and that has been a good reliable and fast laptop. It also can run World of Warcraft with the integrated Radeon GPU in which the GPU/CPU combination was what i was looking for. I needed for it to be able to run games, and so when I saw that model, I was like COOL, it will run WoW under normal settings and its price isnt bad.
So I have bought computers from Wal-Mart, Staples, Best Buy, Radio Shack, Tiger Direct, and Newegg and as far as junk computers go... you just have to know what you want and not be manipulated into buying something based on a sales clerks suggestions. My worst experience has to be buying the HP Pavilion Full Height Tower from Staples as an open box under clearance terms so I wasnt able to return it like the prior customer did. I had to take a $150 loss and sell it to a coworker who wasn't a gamer and didnt have money to afford a brand new computer, so to him he got it for like 50% off back then and it replaced his 486 SX 25 Mhz running Windows 3.11 on 4MB Ram, 120MB Hard Drive, and 14.4k modem, and he was so excited to connect to AOL at 56k vs 14.4k.