Try this ;-)
XBMC is available for all platforms from http://www.xbmc.org and will let you include multiple video sources.
Set it up to broadcast on the network.
System > Network > Services > Share Video and Music libraries through UPNP
If you want, also check 'Allow control of XBMC via UPNP'.
Create a library: From XBMC home screen, select 'Music', add source, choose a music folder and give it a name. Right click the folder and select 'scan items to library'.
Video libraries: check you have adhered to this for building your video library:
Repeat the library process for your video content.
And finally... It sounds to me like network discovery has not been enabled.
Network discovery is a network setting that affects whether your computer can see (find) other computers and devices on the network and whether other computers on the network can see your computer. By default, Windows Firewall blocks network discovery, but you can enable it.
Open Advanced sharing settings by clicking the Start button , and then clicking Control Panel. In the search box, type network, click Network and Sharing Center, and then, in the left pane, click Change advanced sharing settings.
Click the chevron to expand your current network profile.
Click Turn on network discovery, and then click Save changes. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
And you should be good to get moving media!
Make sure your computer and handset are on the same subnet and have a go at streaming some media.