Thanks so much for your replies. I wasn't sure if one worked better generally than the other. I will be doing this in my apartment, so come to think of it, I am guess the boom will pick up other random sounds that may occur in the building.
I just responded to your post about cardiod lavs. But if podcasting from your apartment is your application, why bother with the hassle of a lavalier?
If you are the talent, consider mic technique, not just mic selection. There are a lot of high quality mics on the market that are suitable for podcasting. Note: I think you should avoid most of the podcasting-in-a-box solutions. It is not too hard to assemble your own audio interface, mic, and DAW software.
If you are on a Mac, many podcasts are done with GarageBand, included with OS X.
There are tons of quality firewire interfaces on the market.
For a mic, you could start with a Shure SM57 or SM58 at under a hundred bucks. Even if you move on, almost everyone keeps a few of these workhorse Shure mics in their kit.
If you are building a dedicated podcasting studio, take a look at the Rode line. A lot of bang for the buck. I don't own, but would consider, their Broadcaster model, along with the PSA1 boom arm.
I'm not crazy about the concept of USB mics, but for a dedicated application such as a podcast, and simplicity in an apartment recording studio, this one might be worth considering.
If podcasting is your application, I would not think lavalier is your best choice. You would never see a lavalier used much in a radio station, for instance. You will see them in on air TV, but usually only in cable access work or local TV news, situations where usually nobody pays much attention to sound.