I've done quite a bit of recording work so I'll share what I know about what will introduce noise into recordings.
Bad room acoustics of course. Seems like you are already working on that. :) Also make sure there are no noisy appliances in the room, which may include your computer depending on how loud it is. Appliances can also introduce vibrations into the floor or whatever surface your mice is resting on, which I'll get to in a second.
Also, if you want to make a cheap pop filter, just get a hanger and pantyhose. Works just as well as a real one. Sometimes a pop filter isn't necessary if you don't talk directly into the mic by having it at an angle.
When you have a mic on a boom stand a shock mount is useful because it suspends the microphone in mid air so it's not receiving vibrations from the floor and the boom stand itself. The vibrations that are absorbed by the pop filter do get transmitted to the boom stand because it's physically attached to it, and that'll create some added noise too unless you have a shock mount or the pop filter is not attached to the boom stand.
Make sure you have a good sound card because cheap ones (especially those RealTek integrated sound cards on motherboards) have a really bad analogue to digital converter and/or poor signal-to-noise ratio which can create a constant hiss. Also most consumer soundcards only have the 1/8" microphone jack when you need a big 1/4" plug for your mic. Yes, you can get adapters of course, but you may also need a preamp if your soundcard picks up the microphone too quiet.
There are two types of microphones: dynamic and condenser. Condenser mics are very sensitive and will pick up every noise in the room, whereas a dynamic mic won't. This is also why I prefer a dynamic mic for recording voice unless I have perfect recording conditions. There's also the issue of condenser mics needing phantom power, but that also depends on kind of soundcard or preamp you are using which may have that built in.
Oh, and mics have different kinds of pickups which refer to the angular range that the microphone will capture soundwaves from. You'll probably be looking at etiher cardioid or hypercardioid microphones. Zzounds.com has good product descriptions for their microphones that explain the difference. Here's a good summary of the different pickup patterns:
www.uncleslinky.co.uk/polarpatterns.html
As far as the set up I used to record my video, it's a $60 Shure dynamic mic that I got from Zzounds.com. It's on a cheap boom stand plugged into an Audigy ZS 2 which has a front bay for audio plugs and also works as a preamp. The room has a noisy computer so I had to move the mic to the other side of the room and then recorded it standing up. The room is small and I have a lot of stuff in it so the bathroom acoustic effect is gone. Oh, and I didn't use the pop filter.
If you don't have a good sound card I may recommend getting a USB mic. I've had good luck with the Samson C01U Condenser USB mic.
Hope that helps. If you have any questions regarding audio let me know.
