Quality lowers after rendering

Let me start off by saying that I'm kind of new to Sony Vegas.
I do understand how to use it, but I still have to learn alot.

So my problem is:
I made an intro for my new Youtube account with Adobe After Effects.
I wanted to add a song to it, and then render it to a .wmv file
so it would become a 3 to 6MB file, and not like the 1GB file that
I get after rendering it in After Effects. So I imported the .avi
file that I made in AE. Added the song. Checked the Project Video
Properties (HDV 720-30p, Pixel format: 32-bit floating point full
range, Composition gamma: 1,000 linear, Full-res Rendering quality:
best, Deinterlace method: Blend fields)

Then I went to Render As and chose these settings:
Windows Media Video V11: 6Mbps 720-30p Video
Video tab: Mode CBR - High Def 1280x720 - Frame Rate 29,970 NTSC -
Video smoothness 100 Sharpest
Bit rate - 6 M
Video Rendering Quality - Best

The video before rendering looks just fine, good quality.
It has a red background, good quality.
The text in the video looks good too, nothing wrong with it.
But after I render it to .wmv the quality just gets poor.
The red background doesn't look smooth anymore.
It looks like there are some kind of circles with different colors
of red, and when the video fades out you can see them changing to
grey/black. And the text is kind of blurry too.
I'm just frustrated here at home because nothing works.
I've tried different formats (.mp4, .mov) but they just end up
looking exactly the same: blurry text, red circles in the middle.
I don't know what else to do and nobody really knew a solution so
I thought I'd give it a try on a forum.

If you guys know any solution, and keep the good quality after
rendering then I'd love to hear it.

I have my video here so you could see how it looks like:





After the actual intro it has a 20 sec black screen
because I didn't cut it off yet, but don't mind that.
If you can't really see the circles then you should put
it on full screen.

Sorry for my English, I'm Dutch so I probably made some grammar
mistakes.

Hi Steve,

Sorry I forgot to tell you that.
I'm using Sony Vegas Pro 12.

I adjust the settings as you told me to.
Changed 32bit to 8bit and chose the Mainconcept AVC format (.mp4).
But nothing has changed. I'm still getting the same circles in
red, although they now are a little less visible. I looked for the
Sony AVC Internet format but the only options I get to choose are:
- Memory Card QVGA/PSP/SD NTSC
- AVCHD 1080p
- Blu-ray 1080p

Is there any other solution?
I first thought that After Effects was the problem, but the quality
of the rendered video from After Effects looks just fine. So it really
has to do something with Vegas Pro. Maybe something wrong with the
color settings? I can send you my rendered After Effects video file
if you'd like to? Then you can try it out.

Thanks for the help!