I found a safer and easier way to eliminate the problem.
I have Antec 300, and i had exactly the same problem, I could hear static through front panel audio(HDA) when i moved mouse cursor, or hovered over the links in browser, and it was a DISASTER when i was listening through the music.
This was the first computer i made, so i was really impatient to try out my new config so i slapped everything together without paying attention to the cable management, and since audio connector is positioned all the way across the motherboard - Front panel Audio cable was hanging between CPU and videocard, and as I said - static was terrible.
Yesterday I disassembled my whole rig and decided to redo cables, and i put the audio cable around the motherboard and tucked it in there so that it wouldn't fall out. When i plugged in my headphones i couldn't hear any static at all -- even with my headphones and system volume turned to max.
So.. no need to cut any wires and void your warranty, or buy expensive sound cards to get rid of the static, simply put the cable away from from all "calcuating" hardware, or if you have space - tuck it behind the motherboard.
Case: Antec 300
Motherboard: GIGABYTE GA-EP45-UD3R
CPU: Intel Core2Duo e6400 2.13GHz @ 3.20GHz
Cooler: Thermaltake Big Typhoon
RAM: 2*1GB G.Skill 1066 DDR2
Video Card: Apollo HD 4850 512MB
PSU: PC Power & Cooling Silencer 450w
OS: Windows 7 Ultimate 32-bit (Build 7100)