I can vouch for the Plantronics 640 being excellent and it cost between $70-$100 dollars these days. Be careful Cingular customers - I was in one of their stores the other day and noticed they have a "special" packaged version of this headset. And by "special" I mean it doesn't come with everything and costs more. Say, that IS special. The Cingular package doesn't include the adapters for all the phones or the metal case to keep everything in. Their online store sells the complete package as it's sold in regular stores like Best Buy and Fry's.
I've only had the Plantronics and a Motorola and there is NO comparison. The Plantronics is WAAAAAAAAAAAAAAAAAAAAY better. It's much louder and crisper - not muddled sounding and it stays put (no flopping around). I don't drive a convertible so I don't know how it is with wind noise (though it is not specifically designed to cancel it out) but I can say in a Jeep (enclosed) flying down the highway (read loud tire noise) there is no problem carrying on a conversation. Same is true in a noisy cafe during lunch hour. Everytime I've thought the person on the other end might have a hard time hearing me 'cuz I could hardly hear myself think, I've asked and everytime I've been told I'm loud and clear. I've actually got it turned down a notch or two most the time 'cuz it's too loud!
I just did a quick google search and found a head to head comparison of the Plantronics and Jabra you might find interesting...or not!
http://www.everythingtreo.com/forum/blueto...640-a-4430.html (I'll save you the trouble if you don't want to read it...conclusion: Plantronics was the guy's favorite.) Smeg's had both so his opinion is worthy as well.
Fun fact: the bad guys on the TV show "24" were all wearing Jabra jx10s this last "day" (season). Made me laugh and I thought of Smeg everytime they showed up on screen!
Devices: T-Mobile MDA (Cingular SIM), i-mate SP5m (sitting in a drawer at the moment while I attempt to migrate to PPC permanently), Cingular 3125 (unlocked and in use on T-Mobile), Motorola MPx220 (retired), Motorola MPx200 (retired)
Accessories: Plantronics Explorer 330 & 2G Patriot Micro-SD (use w/MDA), Kingston 2G mini-SD used in SP5m, Plantronics Discovery 640 & 2G San Disk micro-SD (use w/3125), Jabra A210 BT adapter + Motorola HS805 (retired)