Ok, I'll take the bait...
I work at Best Buy and I work in the tech bench. I don't know what's going on with your Best Buy, but here we never take more than an hour or so to do a video card install. Yes, it only takes about 15 minutes to install a video card (screws and installing drivers take the most time), but we do have other computers we're working on, so we can't exactly drop everything to install your video card that very moment. Taking a week should not have happened, however.
As for taking three weeks to repair the CD drive: If you bought your computer from Best Buy and you bought a service plan with it, they can get the hardware replaced if it's bad, but they do have to send it off for service? Why? Because different computers use different parts, and there's no way to stock every single motherboard, sound card, type of ram, or hard drive every computer that has ever been sold at Best Buy in a Best Buy. Sure, if you complain to a manager enough, they'll let the techs take the cheapest CD drive off the shelf and install it in your computer so you don't have to wait the two to three estimated weeks for repair, but it probably want match the case and won't have the same specs as the one that was originally included with your PC.
As for having to wait a week for your warranty to switch over, that was BS. The warranty you buy from Best Buy starts the moment you purchase your PC. It overlaps with the manufacturer's one year warranty. Maybe they just do things differently in the Canadian stores?
Now about the harddrive. If you get a new harddrive installed, you have to install Windows on it. To install Windows on it, you have to either own a copy of Windows or have a restore CD that has Windows on it. It's not like Best Buy can just install a random copy of Windows with a random CD key for you. That's illegal. You have to provide that yourself. Since you apparently don't have a restore disc, you have to buy the full version of Windows XP Home, which is $199. It isn't super duper extra special edition. That's the standard full version of Windows XP. However, the vendor that repairs and replaces hardware for Best Buy (here in the states, at least) will typically do a restore when they replace harddrives. Restore discs don't always require you to input a CD key, but will often times require activation over the internet, which is easy to do.
Now, as for someone saying you can build a better computer for half the price now, that is very hard to do these days. You obviously haven't checked the prices of individual pieces of hardware versus buying a complete machine. You can get an HP desktop with an Athlon X2 3800+, DVD burner (with light scribe), 1gb memory, keyboard, mouse, and 250gb SATA harddrive for about $690 after $50 mail in rebate. I would like to see you build a similar machine that comes anywhere near that price. The processor alone sells on newegg for $295, and I didn't even mention a motherboard in the list above.
I will admit, however, that Best Buy's prices on RAM are pretty crappy. Most computer hardware is only marked up about 10%, and on most computers, Best Buy only makes about $100 per sale. When you see the ads where they're selling laptops for $499, Best Buy is actually losing about $300 per sale on those.
Anyhow, I'm not trying to justify the actions of the Best Buy that you went to. I'm just trying to point out other locations do actually take care of their customers. Everyone is human, so there are errors made, but there are definitely some things your local store could have handle more effeciently. The video card thing shouldn't have taken nearly that long. The CD drive, yeah, because it actually has to get sent off. Here's a tip, though. If you have a CD drive that's bad, and you want it replaced under warranty, but don't want to wait, you can usaully just buy a replacement for $30-50 (can get DVD burners for $59) and have the tech bench install it for you under your warranty. We do that when customers request it at our location. Also, I've never liked Circuit City. They always seem to dark and uninviting inside... but that's another story!