Seriously maybe grab limitedsharpen and have a play, but get to know how the programs work *first*.
Try getting some footage, applying say two filters to it in vdub, and then play with the filter settings and see what happens. The try the same thing in avisynth. Try changing the order of filters and see the results.
Get a grounding on how both programs work first by just using a few filters.
Once you have your head round it - *then* download another filter or two and see what they do.
For this sort of work the things you may want to do with footage is:
adjust the black and white points
noise removal
sharpening
resizing
colour correction
at least to get started anyway. so grab some filters that relate to those and try them one at a time, get to know them, see which you like the best, then see what order they work best in and so on.
I guess what I am trying to say in my waffle is don't get caught in the trap of being a 'collector' of apps and filters, pick a small selection of software, then start using it and learning it, and don't download anything new until you understand what you already have.