Internet Explorer in Vista

[pantheratigris]

I recently recieved a complimentary copy of Vista Ultimate. I have installed Vista 64-bit. There is one doubt I have?
Is there any great performance difference between Vista 32-bit and 64-bit?
Secondly
In Vista 64-bit there are two Internet Explorers
One is Internet Explorer 7
and the other is
Internet Explorer 7(64-bit)
What is the difference between the two for I think both of them run at the same speed, so what is the difference?
And what is the use of giving two Internet Explorers ? Why didn't they just give the 64-bit edition since I installed the 64-bit edition of Vista?

[iMav]

64 bit is for 64bit processors .... which means more data transfer capabilities and if im not worng 64bit procys can detect more than 3gb of ram .... i dont think there shud be any major difference between the 32bit and 64bit IE .... some technical difference .... thats all