Converting two videos to same format

[ChasVideo]

I have two videos with very different encoding that I want to blend together using VirtualDub or some other basic editor. I know how to use VirtualDub but not any of the others.

The first video is in WMV 9 format:
1920x1080
30 fps
5.744 Kbps constant
YUV
4:2:0
8 bit
Progressive

The second video is in MP4 format:
720x420
BVOP:1
H.263
DX50
880 Kbps
29.970 fps
YUV
4:2:0

I do not want to lose any quality from the 1080P video, so I need to up convert the 720x420 to 1080p by adding some black borders and rescaling.
I also might try distorting both a little bit to something like 16x10.5 format. Or I might do the old pan-n-scan trick of cutting off some of 16x9 video.

I have Xvid4PSP5 and AviDemux but there are so many conversion options I have no idea how to get them both to the same format that VirtualDub will accept.

How to rescale is my problem. I do not understand all the different codecs and all the many different options for them.

I think I want to convert them both to a lossless codec, then do my editing and convert the final product to h.264.

So, what is the best way to get them both to the same format?

[Baldrick]

You can import wmv and mp4 with the virtualdub import plugins.

See http://forums.virtualdub.org/index.php?act=ST&f=7&t=19488 or install the virtualdubaio with all plugins, http://forums.virtualdub.org/index.php?act=ST&f=3&t=23203&st=0 .

[ChasVideo]

Yes, I can. But not at the same time in order to use scenes from both into the final product. To get both at the same time, they must be the same size, codec, fps and bit rate. I cannot figure out any settings of a video converter that will make all those parameters the same for both videos.

[Baldrick]

I was thinking that you can resize and add black borders with virtualdub. And export with exact same settings. Then join.

Or maybe make an avisynth scrip that joins and resize everything. But I can't help with that.