connecting a passport to an airport extreme

FWIW ... I currently have two My Passports connected to 4th gen Time Capsule. I use one for TC archieving and the other as a NAS device. Both are formatted for HFS+ and work perfectly.

Yes, sorry, I should have added that point ... except when it comes to using external USB HDDs for Time Machine. Apple does NOT support them for the Extreme, but DOES for the Time Capsule.

I can connect the WD passport to the Extreme - YES

Yes.

I can set up Time Machine to use it for back up purposes - Yes, but Not Supported by Apple

Yes, and yes. ref: Time Machine doesn't back up to AirPort Disks

How do I access the WD passport from my Windows 7 computer?

I've formated the passport as exFAT, the airport extreme sees it, but I don't know how to access it. There doesn't seem to be a way to adjust the name of the share. It has spaces in it... "WD My Passport 1234 5678". I've renamed the airport extreme to no longer have any spaces or symbols in the name... I can't ping the name of the airport... I can ping it's IP, browsing to it's IP does not find any shares.

I'm sure that Tesserax will also confirm that the AirPort Extreme cannot read exFAT or NTFS formats. It can read FAT32 or Mac OS Extended (Journaled).

http://support.apple.com/kb/HT2426

To add a bit more about Time Machine backups to a drive at the USB port of the AirPort Extreme.....

Some users seem to be able to make this work somewhat. Some users have some success and some have no success.

Having tried this myself as an experiment a number of times over the past few years whenever a new firmware update becomes available or merely out of curiosity.....I remain solidly in the "no success" category. But, your results may vary if you want to try this.

Thanks for the quick reply, any idea if this will work if I format it as mac os extended (journaled)? Will my Win7 boxes be able to read and write to it? The drive is too big to format as fat32. I've tried on a virtual xp box and it would only let me format as ntfs. Win7 lets me do ntfs or exFat.

if I format it as mac os extended (journaled)? Will my Win7 boxes be able to read and write to it?

Yes, that would be the recommended format as long as the drive is attached to the AirPort Extreme. Both PCs and Macs will be able to read and write to the drive.