How to get ATmega32(L) native USB support for programming?

Hi everybody,
after browsing several boards and websites ( e.g. software:bootloaders [Electronic Thingies for Fun Stuff] ) telling me how to successfully flash an ATMega32(L) board and use it as Arduino IDE compliant device, I’m still stuck with the need to program the board externally (JTAG, AVR-ISP, …).
But in fact this ATMega32 board has a mircro USB connector, which is connected to PD0 (USB D-) and PD2 (USB D+).
Unfortunately my windows doesn’t recognize the USB Device (ATMega board), when I connect it to my Windows7 x64.
The bootloader (e.g. ATmegaBOOT_168_atmega32.hex) with the blink-sketch “burnt” via ISP is working - the LED blinks.
Does anyone have an idea, if there is an ATMega32 “Arduino” bootloader, which natively supports the ATMega32-USB so I have programming and the serial port via the onboard USB connected to PD0 and PD2?