USB 1 only goes up to 12Mb/s = 1.5MB/s raw bus rate (a bit less for the effective rate since the raw rate includes the command overhead). So you are definitely using USB 2. USB 2 is older than Ubuntu anyway.
The module for USB 2.0 support is
ehci_hcd. I think that all Ubuntu kernels include it as a module, but I'm not sure, it may be included in the kernel image in your version.
You can check what USB controllers you have by running
lspci; you're likely to see several USB1 controllers and one USB2 controller (USB2 controllers can handle more devices, so most computers can do with a single one).
lspci -v will show what driver is handling each PCI device.
The easiest way of finding out in detail what the disk is connected to is to run
udevadm info -a -n /dev/sdb (or whatever the block device is corresponding to the disk). You can also look up the information directly under
/sys (that's what
udevadm does); look where the symlink
/sys/block/sdb points to.
There is also some information in the output of
lsusb -v. For a hard disk, there'll be a line
bInterfaceClass 8 Mass Storage. The
bcdUSB value is the version of the USB protocol:
2.00 for a USB2 device. The bus number identifies which hub the device is connected to (which may be the root hub inside the controller).