Computer+microphone problem - what's wrong?

I want to be able to speak into a microphone and record into my computer. But I can’t, and I can’t figure out why.

I have an HP Pavilions running Windows XP Service Pack 1 (I know, I know.) I have a microphone jack on the front of the computer.

What I’ve tried:
I downloaded Audacity and tried to record directly into that program. No joy. I don’t see any variation in levels when I speak into the mike, and playback just gives me a hum. I tried two other microphones - same thing.

I went to the Windows Sound Recorder, hooked up my mikes and tried recording voice. Same problem – no audio, just a hum on playback.

I’ve gone to Control Panel/Sound and Audio Devices/Audio and checked the the correct default device (Realtek AC97 Audio) is checked on both Sound Playback and Sound Recording. The mike volume is selected, and it is set up fairly high (over half-way up the sliding scale.) Under the Voice tab, the correct default device for Voice Playback and Voice Recording is selected, and the volume appears to be selected correctly. The Hardware tab tells me that my Realtek AC97 Audio is working correctly.

I have a feeling there’s just something I’m overlooking. Anyone have any thoughts on something else I could try??? I really want to do podcasts, and it would be really nice if I could record straight onto my computer instead of having to record to another device and do a real-time transfer from it to the computer for editing.

Any help would be appreciated.

You should also have one on the back of the computer. Did you try that one, as well? If you don’t have a rear-panel jack ( and even if you do), it’s possible that the cable that connects the front-panel jack set to the mainboard has come loose. If you feel comfortable doing so, open the case and check the cable–follow it back to the mainboard and make sure the header is firmly seated. If it’s completely off, you may have to find the mainboard pinout diagram (probably available on HP’s website) to locate the proper header.

Or just plug it into the back one, anyway.

Check the following:

Open Volume Control
Select Options->Properties
Select “Recording”
Make sure “Microphone” is one of the selected options
Click OK
Make sure “Microphone” is checked in the main window

I’d already checked that, thanks. Opening up the “Sound and Audio” bit on the Control Panel appears to bring up the same sort of volume controls. I’ve checked them both.

I know about the jack on the back, and no, I haven’t tried it, but that’s a valid suggestion. I’ll do that just for the sake of completeness, but I’ll be pretty surprised if that’s the problem.