If you are ONLY after the MIDI ports, try and find a standard connector for it:
They cost £5-10 and have a 2-row 15-way D-sub at one end (NOT a 3-row 15-pin D-sub like VGA!) and 2 x 5-pin DIN MIDI ports at the other.
The big box you talk about sounds like the break-out box that you get with lots of soundcards today - They are a gimmick, but can be nifty (I can remote-control my compy with my SBLive! IR remote

).
Mine has mini-DIN plugs for MIDI connectors and has all sorts of Line-In and SPDIF crap all over it (Most of which I never use!). However, plugging non-digital stuff in has really ****ty quality compared to plugging it directly to the sound card, so as I said it's a bit of a gimmick.
Generally, the only cards worth considering are SB Live/Audigy atm (They really ****ing suck, but they still blow almost everyone else out of the water, sadly).
However, many mobos, esp. nForce ones, have incredibly good sound hardware that is equal to all but the top-of-the-line sound cards.
If you have this, stick with it - there's no point in getting another card.
Also, if you're gonna be doing some hardcore sound stuff, make sure you get a card with ASIO-certified drivers; Only the top-end SB's have that, but good alternatives are the Terratec cards - Cheaper too, but not so great all-rounders as SB's.
If you have an old SB16-type motherboard 'tho, pick up a cheap PCI sound card. You'll loose DOS compatibility (Because everyone is too ****ing cheap to build it into their cards!!), but you'll get much better quality (Lower CPU usage, more than 2 sound channels etc..).
My SBLive Platinum is going pretty cheap these days and you'll get all the MIDI cables with it too!