For this you'll need a copy of Kerio Personal Firewall. It's free for personal use, for business use you need a license.
http://www.kerio.com/kpf_download.html
If you have other personal firewall software installed you're going to need to uninstall it to avoid conflicts. I'm going to install you have some knowledge of how to operate a personal firewall in terms of setting the rest of it up - this is just for banning IP's using Kerio. If you don't, there's a fairly complete help system installed with it to get you started.
1 ) Right click the system tray icon and choose configuration
2 ) Go to the Network Security Tab
3 ) Click Packet Filter
4 ) Click Add
(The Important Bit)
IP Groups are a way of combining all banned IP's into one easy to manage group - you will be able to say Block Banned IP's rather than setting up the whole set of rules individually for however many users you want to ban.
Remember that some users on dialup and DSL/cable may have non static IPs, so blocking a whole group of IP's may be the only way to get rid of them. This means banning the whole subnet of IP's the user might connect from.
For example, if their IP is 10.0.0.3 you would ban 10.0.0.1-10.0.0.254. Do this by selecting Address Range instead of Host in the steps explained below and entering the first and last IP in the range. Only use the range option if you are sure no other users from that range need to connect.
e.g. If you are serving on a LAN and want all LAN users except one IP to be able to access the server, you would use an IP ban, not a range ban. If you are serving over the internet and want to ban one user and don't have logs of any other users from the same range who you still want to allow access to, block the whole range.
5 ) Click IP Groups.
6 ) Click Add and enter a group name such as "Banned Abyss Users". You can leave the description blank or enter extra details here if you want.
7 ) Leave the Type option set to Host and enter the first IP you want to ban here. Click OK.
8 ) For each additional IP you want to ban, click Add, then select the group Banned Users and enter the IP to ban as above. Make sure you select the group banned users or the final steps will not work correctly.
Now you have all the users to ban set up, you are ready to create a banning rule.
9 ) Click Filter Rules, then Add.
10 ) Enter a description for the rule - something appropriate
e.g. Ban Users from Abyss Webserver
11 ) Click Browse and browse to the .exe file for Abyss
e,g C:\Program Files\Abyss Web Server\abyssws.exe on my system.
12 ) Leave the group name as Default, or enter something like Abyss Webserver Rules. All the Group does is group similar rules together, it doesn't affect how the ban will work.
13 ) For protocol, click Add and select TCP, the default.
14 ) If you want to ban the user from your machine completely, not just Abyss, skip this step. Otherwise, in the Local section, click Add and enter the port number your server is running on.
15 ) In the Remote section, click Add, then select IP Group and the group you used to enter the banned users in.
16 ) Select Incoming and Deny from the checkboxes at the bottom of the dialogue.
17 ) If you want a box to pop up when they try to connect, click the "Show Alert to User" box.
18 ) Click OK.
Bingo! You've just blocked all the bad guys from your server
To add further banned users in future, follow steps 1-5 and 7. Skip 6.
Hope this helps! I can add screenshots if someone has somewhere to put them.