I'm trying to connect my IQ2 to my Windows XP desktop by USB cable.

Does anybody know which driver(s) I need to get for Windows?

http://www.akexorcist.com/2013/04/android-dev-tips-adb-driver.html

Scroll down

USB Drivers to do what?

A SmartPhone USB port connected to a PC can be used as

Mass storage mode (act as USB Flash Drive) allowing you to read/write to the external/SD memory of the phone

Tethering, allowing the PC to use your SmartPhone Internet Connection

Reverse Tethering, allowing your SmartPhone to use your PCs Internet Connection

Media Sync, allowing a program on you PC to access the user data on the SmartPhone

or as already posted, a communications port for ADB.(Android Debug Bridge)

While you can connect directly to your SmartPhone via USB, it's also possible to make similar mode connections (or emulated or simulated mode connection) via Bluetooth or WiFi.

http://www.akexorcist.com/2013/04/android-dev-tips-adb-driver.html

Scroll down

Thank you.

USB Drivers to do what?

Thanks for taking the time to respond. I'm just trying to transfer files to the SD card on the phone.

You'll need to enable Mass Storage mode on you SmartPhone so it will emulate a "Flash Drive" or USB Storage Device (and USB Debugging is disabled). Usually a dialog will pop up automatically when you connect your SmartPhone to a active computer's USB port and ask you if you want to "turn on USB Storage".

Some people have issues reading the memory storage directly and instead use MTP Media Device and transfer files via an application.

The Windows XP (SP2 or SP3) PC with USB 2.0 Ports may already have the driver installed supporting Flash Drive (or USB Mass Storage Device).

If not, then you may want to visit official driver sites. I mention 'official' here because getting them from unofficial sites is a great way to install modified drivers that will later fetch and self-install malware and Trojan virus code.

Microsoft Support

A computer that is running Windows XP cannot detect a USB

flash drive, an Apple iPod, or an external hard disk drive

support.microsoft.com

also...

A SuperUser forum post suggested "downloading Driver Identifier and let that tool find out the hardware id of the USB-device you have in your machine .. it will also yield multiple driver-download-urls directly", though you may find many of the 'links' broken as few sites still support XP.