I also had a terrible problem with the plosive "p" popping out of my mouth. I needed a solution so I started to visit podcasters tutorial web sites to see how they solved the problem.
Some of the podcasters recommended the Snowball microphone from Blue Microphone. I loved the look of the Snowball but I didn't need the whole rigging shebang.
I went to the vendor web site and they had a smaller model called the Snowflake. It was just the right size for my needs. This is Kristin giving her review of the Blue Snowflake Microphone:
It is a USB connected microphone. I can just plug it in and get going. It does add a nice tone to the voice. This microphone is Mac and PC compatible.
According to the web site you can use it for:
Perfect for dictation, field recording, lecture recording, narration, presentations, Vocals, Music Instruments, Podcasting, VOIP (such as Skype and Vonage), Voice Recognition Software, Multimedia; ideal for AIM, Yahoo!, MSN, iChat, ooVoo and Google Talk.
I bought the Snowflake for $79 retail but you might find it less online at places like Amazon.com. It is more expensive than a computer mic but I consider this an investment so it was worth it to me.