SO.......im assuming it has been working but has died since you installed ''W7''..??
im almost 100% sure a new OS wouldn't prevent the system speaker from bleeping as this is BIOS related... make sure the connection has not been knocked, try removing then replacing the speaker header from the board.
check the speaker connections on the cone itself too....
if all the above fails & its really that important to you, you'll need to get yourself another small speaker cone & wire it into the header, if it still wont work its a problem with the board, in which case there is no remedy..
im sure there's no BIOS option to disable the system speaker, but if you've not been in there i'd say its either a perished cone or faulty connection.
My Computer
Computer Manufacturer/Model Number
myself
OS
SEVEN x64
CPU
Q9450 @ 3.6GHZ 1.34v
Motherboard
ASUS P5K PREMIUM P35
Memory
8GB 1066 buffalo firestix @ 1152mhz CL5
Graphics Card(s)
Sapphire HD 5970 + GTX260 (physX)
Sound Card
Creative X-FI Xtreme Gamer
Monitor(s) Displays
SAMSUNG 20'' & SAMSUNG 23'' (dual screens)
Screen Resolution
2048x1152 & 1680x1050
Hard Drives
1x seagate 160gb IDE & 1x seagate 160gb SATA
PSU
XCILIO 850w (78A)
Case
CM590 1x 120x38mm & 2x92x38mm / 4x 120x25mm
Cooling
AC7 PRO @ 92x38mm blower, Lamptron military bus bay controll
4 x 4GB DDR3-1600 Corsair Vengeance CMZ8GX3M2A1600C9B (16GB)
Graphics Card(s)
MSI GeForce GTX770 Gaming OC 2GB
Sound Card
Realtek High Definition on board solution (ALC 898)
Monitor(s) Displays
ViewSonic VA1912w Widescreen (VGA)
Screen Resolution
1440x900
Hard Drives
OCZ Agility 3 SSD 120GB SATA III x2 (RAID 0)
Samsung HD501LJ 500GB SATA II x2
Hitachi HDS721010CLA332 1TB SATA II
Iomega 1.5TB Ext USB 2.0
WD 2.0TB Ext USB 3.0