Hi there welcome to linux.
As far as i understan, you have already installed linux and its working fine ona second hard drive. You are able to connect to the internet through a dialup.
If not please give details like the distro. for eg.
When u install linux it has a boot loader lilke grub or lilo that recognizes the windows and hence you would have a choice to select from them.
If i am way off in answering ur question just ignore this reply