Having two computers with Windows 2000 might simplify this more, but it should be quite simple either way (unless there is a problem)
To share your printer in 2000, I figured I'd copy and paste some stuff to save some time. Here's a quick overview:
To share your printer
Open Printers and Faxes. (Start/Settings/Control panel/Printers)
Right-click the printer you want to share, and then click Sharing.
The options you see on the Sharing tab differ depending on whether sharing is enabled on your computer. For instructions on what to do next, click the option that describes what you see on the Sharing tab.
NEXT...
On the Sharing tab, click Share this printer and then type a share name for the shared printer.
If you share the printer with users on different hardware or different operating systems, click Additional Drivers. Click the environment and operating system for the other computers, and then click OK to install the additional drivers.
Drivers for users running other versions of Windows (Windows 95, Windows 98, or Windows NT 4.0) are located on the Support CD. Printer drivers for Windows NT 3.1 and Windows NT 3.5 are not included.
Click OK, or, if you have installed additional drivers, click Close.
Keep in mind, you will probably need Windows 98 drivers as well and you can use "install additional drivers" so that the computers can negotiate printer drivers.
Also, to share this printer, you may have to setup users. In which case you can easily make/enable a guest account to share printer access or give your sister computer exclusive access - It's up to you. If you have questions about setting permissions and users, look no further than
www.google.com or more friendly people here to help you out more.