album art downsize?

I have a large folder of lossless music, organized into subfolders by album. each of these folders has one or more jpg's or png's for cover art. I'd like to convert to create a separate lossy folder for my portable, which is easy enough. however, when I convert to .ogg, I still have the original album art. I would like to find a way to downsize the albumart for my separate .ogg folder to save space for my portable. any suggestions on how to do this en masse, while retaining the organization?
this is my current folder structure:
E:\Music\FLAC\%albumartist% - %album% (%year%)\

music files:
%artist% - %album% - %discnumber%.%tracknumber%. %title%.flac
art files:
%albumartist%-%year%-%album%.*

or is this something better attempted with another program? I have been using foobar to do my conversions, but i recently reorganized all of my music.

For the conversion of your music files you have to use another program. MP3tag only tags.
For a fairly automatic process:
You could convert the files to the same folder where the ogg files are.
Then you load all files into mp3tag.
Then you filter for the non-ogg files.
Use Convert>Tag-Filename and a mask with an absolute path in it describing the target folder for the lossy files, e.g.
k:\lossy\%artist%\%year% - %album%$num(%track%,2) - %title%

Depening on the features of the conversion program you will still have the covers embedded in the files.
If this is not the case then you should embed the covers in the non-ogg-files first before you move them to the new target folder.
And: unless the target player has problems with certain files sizes the cover size should matter a great deal.