Can I use sql express to run WSS on windows server 2008 and if I can would this be a wise move?
I can't give you a definitive answer, but here's something that happened to me once. I once installed Team Foundation Server on a Virtual Machine, and forgot to install SQL Server first. I expected the install to fail, but let it go, just in case.
It turns out that it installed SQL Server Express, and seemed reasonably happy with the decision. I don't think it got Reporting Services and such, but it seemed happy enough.
Go over to technet.microsoft.com and find the system requirements and install documentation for WSS. See if this is a valid configuration and what the issues might be.
Have a read of this article. You can use Windows Internal Database that's built into Windows 2008 as your database server.
The primary limitation is that SharePoint's application, web front end, and database roles all have to be installed on a single server. As usage of SharePoint increases, this could become a performance bottleneck. It's also not easy to move to a farm deployment - you would have to use SharePoint backup, reinstall SharePoint in a farm role, then restore your SharePoint data.
On the other hand, it's very quick to get up and running. There are also no database size limitations (a previously common misconception). You can use SQL Server Management Studio Express to manage the databases.