Sound/microphone problem

Hi. I've had my computer for years, and for almost as long as I can remember the front ports have all been broken (this was caused by the chip inside breaking apparently). So last week I sent it in for a new case. It's now back, but I can't remember how to configure the computer to use the front ports. The man in the shop said I had my sound configured strangely, but didn't go into details. I can only get sound working from the (new) front port, and my microphone only works from the (old) back port. I don't know why sound isn't working from the back any more; seems rather odd to me. (If it's relevent I also had a new graphics card, new RAM and a new PSU put in). Let me know what information you need.

I'm so grateful for any help! Many thanks in advance,
Thomas.

EDIT: Also while I'm here, apparently XP isn't recognising all of my RAM (I have 2 x 2gb DDR2 memory chips, but only 2.75gb are showing in System Information). I was told it could be to do with out-dated BIOS drivers or something - I've since checked and they were last updated in 2005 according to www.biosagentplus.com. If I should post this in a new topic let me know!

 

Just found this in my tray (never seen it before, must have been added by the "expert"). Why is it saying no mic connected when one is plugged in? Also there is no blue socket on the front yet apparently something is plugged into it?