Asus X48 motherboards?

C'mon,man, are you telling me that all the quad cores are going to the bin? just because i5 & i7 are better than them? we cannot be chasing the technology it changes every second,the day after tomorrow those excellent processors are going to be in the same situation as the 775 sockets today   .
Apart from that,
The i5 platforms seems to be around the same price as the x48 or p45 motherboards,i dont think its a bad idea,but 1366 processors are now between 250 and 900£, which its absolutely crazy,and then we'l get i9 or something,and 1366 will be forgotten...look http://www.guru3d.com/news/intel-sixcore-core-i9-photos... .if u know what i mean

If you want to wait then you can't buy anything because there is always a new stuff around the corner.
But if you are going to buy a new system now,its a mistake to buy LGA 775 since they aren't produced anymore,and yes as you mentioned i5/i7 will have the same destiny as 775 in the future when new CPUs come out,that's how technology goes,every day a new stuff comes out.
So go for the i5 750 it performs well and its price is good too  

Yes it's true, theres always new stuff coming out.i was comparing some 775 systems with the p55 and i think the P55 just eats the 775
check this out,http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=357...

i dont understand why it has a low bus speed? maybe it doesnt matter,and u can take the multipler up to x20,and up to 4.2,but i dont really understand that....

here,what about this:http://www.scan.co.uk/products/Asus-Maximus-III-Formula...
I didn't compare all the assus yet(i'm an assus fan) but it looks good,  

Yes that ASUS model is a good choice