Firstly, given the mass-market take-up of 802.11b, I'm going to make the assumption that you're either using a 802.11b compliant wireless network card or a 802.11g-draft compliant network card which is 802.11b backwards compatible.
There are definitely a number of ways that you could approach your situation and wired is obviously a possibility but if you'd like to retain the freedom and mobility that you have during the day whilst using the wireless network then what I would suggest is another wireless network. The simplest and most cost-effective way to achieve your objectives would be to purchase a low-end access-point such as the NetGear MR814 (or similar access point in the SOHO range: Linksys, DLink, etc.) These access point routers are very easy to configure and tend to come with both a WAN port (to share Internet connectivity) as well as a built-in 4 port 10/100Mbps switch which is perfect for providing network connectivity for legacy wired devices such as a desktop.
With regards to your question about laptops and multiple wireless networks, definitely. If you're running an operating system such as Windows XP (SP1) then it's simply a matter of right clicking on your wireless network connectivity icon next to the windows clock in the taskbar and selecting "View Available Wireless Networks" and then selecting the network that you would like to connect to. If you're using an older operating system with some proprietary software to manage the wireless card then you should look to set up multiple wireless profiles.
This was first published in June 2003