Let the hive mind of Engadget get that for you.
"I've found myself using my PC for a lot of conversations lately, and I'm also considering recording a podcast to share with anyone who will listen. There are tons of USB headset / microphones out there, and I'm hoping someone has some solid recommendations based on experience. I'll consider both headsets and standalone mics, by the way, but I'd like to keep the bill under $100 if possible. Help!"
Had my hands on 750 since last week, beautiful Treo with WM 5.0... but I'd prefer it come with wi-fi.
Also for 680, it does have bluetooth. I had the 680 for about 3 weeks now, it looks pretty much identical layout/form-factor as to 750, the keyboard feels really nice.