When you add the font to Windows, Inkscape and most other editing programs will list it.
From
http://support.microsoft.com/kb/314960: To install a font, follow these steps:
Find the font you want and download it to your hard drive, flash drive, etc.. Put it somewhere easy to browse to, like c:\.
Click Start, and then click Run (WinXP) or in newer versions type into the command window.
Type the following command, and then click OK:
%windir%\fonts
[NOTE you can also do this from Control Panel--Fonts]
On the File menu, click Install New Font.
In the Drives box, click the drive that contains the font that you want to add.
In the Folders box, click the folder that contains the font that you want to add, and then click OK.
In the List of fonts box, click the font that you want to add. To select more than one font at a time, press and hold the CTRL key while you select each font.
Click to select the Copy Fonts To Fonts Folder check box. The new font is saved in the Windows\Fonts folder.
Click OK.
When you open the Fonts Selection in Inkscape, the new font should be listed.
