You already have a physical home network, I assume (router, desktop connected wired, laptop wireless). Then all you've got to do is some setup using the Home Network Wizard, enable printer sharing on the desktop and install the shared printer on the laptop.
http://www.home-network-help.com/vista-printer-sharing.html is just one of the many links I found with google.
The alternative is to use a network printer (that connects to the router directly): http://windowshelp.microsoft.com/Windows/en-us/help/3b48e8bf-7d8a-417e-8053-6e9cca3528c21033.mspx
I have a wireless set up in my home and often use my laptop in different rooms and would like to use my laptop to remotely print to my main desktop computer. Is this possible? What software do I need?-- I have an HP laptop (HP desktop, as well). My OS is Vista Home. Thanks for any info!