Keep you eye on that Linotype site as Fontexplorer will be the only free font manager, that I know of, available for Windows.
Depending on how many fonts you use, you can make Character styles and share them on various documents. Start a new ID doc, calling it something like FONTS. Go to Window menu/type & tables/character styles.
Hit the little triangle and select "new character style". Click on Basic Character style and Font Family. Select the font you want and name the character style the same as the font, like ITC Leawood, etc. Leave everything else alone. Repeat the New Character Style step for each of the fonts you want. Save the ID doc with a name something like Fonts or Character Styles.
When you create a new ID doc, open the Character styles window and click the little triangle for Load Character Styles. Navigate to that Fonts ID doc and the styles you created will be brought into your new ID doc. You can then select your fonts from that rather than you fonts menu.
I would only bother with the basic font family in the character styles. If you add all the various weights and things like italic, it'll get too big. If you select any text in a doc, the Id character menu will automatically go to that font and you can then select a different form of the font, like bold or italic, from the menu right under the font menu.
Using OSX 10.3.9 & 10.4.11 on a G4, G5 & Intel Macbook