There are many other posts about the pros/cons of Windows Server 2008 as a client machine/desktop/laptop/workstation. Mostly false claims of faster-then-Vista performance, etc. I'm using it on a laptop in x64 strictly for training purposes (not as my main OS) and had to work out these few issues before I could fully use it in that scenario:
- WebDAV Access. Lets say you want to browse to a SharePoint site using UNC path names, or maybe use the new fabulous sysinternals \\live.sysinternals.com\tools way of getting their tools quickly... we'll you can't until you add the 2008 feature "Desktop Experience" which will then add the WebClient service. That service is what allows you WebDAV access to other servers. Don't confuse this with the IIS 7 WebDAV which will allow you to serve up WebDAV content to others. Also note that in Windows Server 2003 the WebClient service is disabled by defaut so if you have the same issues in that OS, enable and set to automatic. It's a security thing since most don't use servers to browse web content.
- Wireless Access. You need to install the feature Wireless LAN Service to use a WiFi card.
- Hyper-V. = no sleep/hibernate (fixed: read update below). It's been said on many other sites, but once you add the Hyper-V role to Server 2008 these features are disabled... making it harder to use it on a laptop.
- Internet Explorer Enhanced Security Configuration (IE ESC). To make the web useable from IE, you need to disable this, which you'll find under Server Manager Summary page where the Security Information is at.
update: Have a GUI do all this for you and more! Over at the Windows Server 2008 Workstation Converter blog.
update 11/15/2008: A reg entry has been found for disabling Hyper-V and allowing power states and sleep/hibernate to work. However, in my experiance, each change of the setting requires a full reboot, so if you disable Hyper-V and reboot, then want to start a VM in Hyper-V, you'll need to change the setting back and reboot again.