usb splitter ? (mbp)

there are only two usb slots in macbook pro as we now
i have more than two devices to connect
so i was wondering to buy a usb splitter - thing that you connect to one usb but it gives you more than one usb slots (sorry don't know how to explain properly)
http://ecx.images-amazon.com/images/I/21LxUMHlVGL._SL500_AA200_.jpg
will it somehow have an impact on the usb slot of my macbook ?
obviously the tension is going to be stronger
i'm planning to connect:

wd external hd (usb powered)
ipod 30 gb (5g)
edirol external soundcard
canon scanner
wacom intuos
mighty mouse

so i need two of those splitters (each side)
will it be ok ?
is there a difference in those splitters ? should i spend loads of money on them buying good quality ones or it doesn't matter ?

thank you

You might want an externally powered USB hub for all of those things - or you iPod won't charge or you won't be able to use certain things.

If all of your USB Devices are externally powered except your Mighty mice & iPOD Then you can simply buy a 4 port USB Hub (USB Powered..not externally powered) & for your iPOD you can use the spare USB port of your macbook pro & Mighty Mouse should work fine through the Hub as well...
But if you have any of your devices which are USB powered then it would be best to buy an externally powered USB hub..

I would recommend a powered USB Splitter. If is only a few dollars extra, and a lot of stuff you might use down the line will require a powered USB connector. I personally went with an external powered hard drive with extra USB built into the case of the hard drive!

thank you guys
i've just bought a logitech external powered usb hub
work fine