Have a look at ebuyer's site click here - first item @ £10.53 plus VAT and P&P is very good value. This is now slightly cheaper than when I bought mine in June.
Also it is USB2 which is much faster than USB1. It is described as 2 ports (on the PCI card) and 3 ports on the front bay (which is where you would like to fit it), but mine actually had 4 ports on the front. Read the reviews and you will see others have also received the 4 port variety. Fitting the PCI card into a spare slot inside the machine and connecting the supplied ribbon cable from the PCI card to the front tray is absolutely no problem and only takes a few minutes (also confirmed in the reviews).
Go for it!!