I appreciate that jailbreaking is not for everyone, but as has already been stated, the only way to replace the iPad system keyboard is to jailbreak and install a keyboard tweak.
Remember, jailbreaking is not illegal and is relatively risk free. It can be achieved with more or less a single click of a jailbreak enabling application on your PC if you are running 5.1.1. There are plenty of folks around who only jailbreak to use one or two little tweaks such as this. Jailbreaking does not prevent you from using any of the standard features of your iPad and it continues to operate as you would expect of a stock device. You can simply install non-Apple approved apps on the device after it is jailbroken.
Here is a link to our "review" of iKeyWi, the 5 row keyboard tweak for jailbroken devices.
http://www.ipadforums.net/jailbreak...-ikeywi-hd-ipad-new-5-row-keyboard-tweak.html
It costs $2.99 from Cydia (the jailbreak app store). This tweak allows you to completely reassign all keys on the keyboard and also provides the standard 5th row and arrow keys
Head on over to our Hacking Section if you need any more info.