It doesn't appear HP has Windows 7 drivers for that system. If you are using ones supplied in Windows 7, they may not be fully functional.
I suppose all I might suggest is to try the Vista Drivers, but if you are using a x64 version of Windows, they may not be allowed.
Also, all the USB ports may not be of the same standard. I do not remember what my Dell's are, different connections may be different versions of USB.