That keyboard is really nice, but don't be mistaken by the fact that it offers alot more than just a simple midi keyboard.
If you only want to use it for modplug, this is way too much for what you want.
It has an audio unit in it which allows you to hook it up to a stereo and use its buildin sounds to make sound with it. Don't get me wrong, thats very cool, and if I had the money left, I would consider getting one too
But to make sure that you won't buy something you don't really need, the question would again be: will it solely be for modplug or other pc things, or will you also want it to use when you're not behind your pc?
If its just for the pc, then there are much cheaper ones that give you the same thing.
There's a product which would be probably one of the better choises if it would be used in conjunction with MPT. Take a look at this for example: http://www.prodikeys.com/
For a stand-alone kayboard, you could be looking at something like this: http://www.rolandce.com/productinfo/productinfodetail.asp?Welke=85
which would probably cost under 70 euro.
Also... Even though MODPlug Tracker allows the usage of a midi keyboard, its not as fancy as it first seems. Yes, you can use it to play instruments directly from whitin mpt and so, but there's a small latency. So you'd be using it for entering notes, and even though thats nice, it will quickly become a problem if either the keyboard is too small to get you to the note you want, or if its too big so you have to move away from your computer for each note you want to insert.
MODPlug Tracker has good capabilities for that on the PC keyboard itself.
Also: if you want to use modplug to control external equipment, then do note that it doesn't work 100% and is product speciffic, as you'll need 3rd party software to begin with. I have a nice Yamaha keyboard with great XG sounds, but I cannot access those banks from MODPlug Tracker. In fact, I can only access the General MIDI bank.
Its a nice toy for sure, and maybe for you it works well, but I wouldn't spend too much money on it at first. Try something small first, or maybe even better, see if you can rent a keyboard so you can try how it works, and if its what you're after.