It is _CRITICAL_ that you get _SOME_ protection for your Windows based OS machine, especially something like Windows 95/98/Me. The routers aformentioned will do some simple stuff like NAT and are good, though for someone with your experience level I would recommend a Netgear RT314 or similar Netgear model. The reason is not superior hardware, but superior technical support.
If you use Windows 2000, make sure that you do not use the machine from day to day as the Administrator - make a trader user or something, and don't give him much "priviledges" and use that from day to day. Also, remember that keeping up with security measures under Windows OS's is a never ending process - in particular, you have to stay alert for Service Packs and Security patches.
I would also encourage you to get NAV 2000 and a software firewall as well.
You should also understand that a cable connection to the Internet is shared. That has two repercusions:
1) It is _WAY_ less safe then dial up, DSL, etc.
2) If a bunch of people at once decide to use a bandwidth intensive web site, like porn, your response from the Internet will come to a grinding halt. This is not likely to happen during trading hours, tho.
nitro