Photoshop Batch

I attempted to make thumbnails out of 100’s of photos using this process:

[LIST=1]
[]Start recording a new action named “thumbnail”
[
]Set crop parameters to 100px 70px
[]Did the actual cropping
[
]Stopped recording of the action
[*]Ran batch on a folder with serial numbering (001.jpg, 002.jpg, 003.jpg,…)
[/LIST]

No where did it give me a chance to set the quality of the jpeg compresssion, so my thumbnails had huge file sizes.

Earlier, I had “save for web” at the end of my action. That allowed me to set the compression settings. But doing so didn’t allow batch to do serial numbering. The file names of the thumbnails always turned out to be the file name of the original file. So I decided to remove that save for web step.

Now I’m stuck between either having serial numbering or having good file sizes. How can I have both?