Because they are different file systems (Ubuntu 12.04 defaults to ext4), you need to be careful about Unix writing to any Windows partition.
Additionally, Windows 7 doesn't share easily even with other Windows machines because 7 started using the homegroup instead of the typical windows network workgroup. Per Microsoft, "Computers must be running Windows 7 to be part of a homegroup. With Windows 7 Starter and Windows 7 Home Basic, you can join a homegroup, but you can't create one."
In the tutorial link that you provided, there was an option to specify the workgroup - but perhaps this only exists in Windows 7 Ultimate edition. In any case, I'm running Windows 7 and do not have that feature.
The first solution that comes to mind is to install Samba. I'd recommend using the Ubuntu Software Center and searching for "system-config-samba." This search will yield the GUI option to configure your Samba server. For command-line, this step-by-step guide will help you install and configure Samba.
You mentioned hooking up your Ubuntu to a wireless router. Make sure that you assign your machine a static IP address/lease using your router configuration utility. Even if your router operates DHCP, you should be able to designate a fixed LAN address by either 1)MAC address or 2)computer name (depending upon your router type/model).
Once configured, Samba should pretty much be ideal for you.
The solution I have used for media service
My network also has an Xbox360 that I wanted to be able to browse and play content from. I purchased a separate NAS (network attached storage). This provided the benefit of also being able to share media globally even with a dynamic IP from my ISP (the device updates a sort of proprietary DNS server with its current IP address). Then the NAS storage handles incoming requests from the WAN through UPnP configuration of my router.
All of my machines, including Ubuntu 12.04 can discover and use the NAS device.