I can offer some guidelines, but they are only my own personal opinion, as there is no "correct" configuration. The following is what I would look for if I was buying one personally:

(In the order you mentioned them):

1. Harddisk. Try and look for a Seagate Barracuda 7200.10. They're high quality, very durable and quite silent. They come in various sizes, depending on your wallet, but aren't much more expensive than other harddisks (Very important it's a 7200.10 and not 7200.9 for example, as it refers to a newer model with better construction).

2. RAM. Here you just want as much as possible, 2 or more GB would be excellent for Poser, although if you use Poser 7 it's not as important as with earlier versions. From what I know, there isn't really a lot of difference between the various manufacturers. Kingston are usually considered good quality. SDRAM is an older type (and currently being phased out afaik) than DDR and DDR2. You have to make sure that the RAM will fit the motherboard, as each type have a different number of pins (the socket is different). The specs for the motherboard will show what type of RAM you need though, so that shouldn't be a problem.

3. GFX CARD. Any modern gfx card will be capable of handling Poser np at all. Typically Nvidia based cards are known to be better compatible with OpenGL than ATI based cards, but I have no personal experience with that. This is where you can save some money IMO. Something like a GeForce 6600, GeForce 7600 or similar would be excellent. I would personally go for a PCI-E based card, as AGP cards are being phased out and most modern motherboards only support PCI-E gfx cards anyway.

4. CPU. Here it depends a bit if you're using Poser 7 or older as well, as Poser 7 supports dual core processors, but the older versions do not. So for instance, if you still use Poser 6 and buy a dual core processor, it would only be able to use one of its processors for rendering. If you want to make your machine as "future-proof" as possible, I'd suggest a dual core anyway though, as it's easier to upgrade your Poser version than it is the processor.

5. Motherboard. Perhaps someone else will be able to give you better advice on this one than I can, as I honestly don't know much about the various brands and models available. What you have to make sure is that you get one that supports the type of RAM, CPU and GFX CARD that you buy. If you're set on an Intel processor, then you'll have to look for Socket 775 motherboards.

6. DVD Burner. These are dirt cheap now, however you might want to consider an external USB 2.0 harddrive instead. I have one that cost about 125 US Dollars (I live in Europe, so I'm not sure of how the prices might be in Canada), but it holds 250 GB and you can bring that with you if you need to go somewhere instead of burning DVD's. It doesn't need any installation or any drivers or anything, you just plug the USB cable into a computer with a free USB slot and you can access it right away (this is only true if the computer has Windows 2000 / XP installed, but I assume most newer ones will).

7 and 8. You answered these already :) Apart from the above mentioned stuff, you might consider a sound card or just go with the onboard sound if that's not an issue for you.

9. Power Supply. A good quality power supply is not to be underestimated. Companies like Akasa make excellent quality power supplies and I'd personally look for a 400+ W power supply (although without getting too technical, it's not the wattage that is the most important, but I don't think it's necessary to worry about that). If you buy an Akasa 400W, that will do you nicely.

Good luck with it! It's a jungle out there, I hope you get something you will be happy with!