A few things:
1. Regardless of what front end or program you choose, people will continuously probe port 21 and other pop/newb ports, it's going to happen, and happen all day, especially on RR's/ WOW's public ip space. ( you can always change your port and share that with your friends/ family and that will cut down on 99.9% of it)
2. Listen to what gabe said, cheap front ends like serv-u, cute-ftp, ect. have more holes than swiss cheese typically and the dev's aren't exactely breaking their balls (Free products with mediorce following.
3. If feasable, sandbox it in a VM with a small linux machine w/ apache and use RO smba shares to the rest of your network (probably stretching now for home security)
4. If you realy don't want to do any of that, pick a larger / well supported server and hope for the best, in all honestly 99% of the time you'll be fine, and do a port change to somethgn stupid.
IE: Filezilla is generally a good windows client & server with decent / regular updates.