NOD32 doesn't emulate sse1 instrucion...is is real?

Hello All,

Today, i found an interesting topic, Anti Emulation tricks....

It seems NOD32 cannot emulate sse1 instructions...

Can any one explain me the following questions...
1. What is sse1 instruction? (pls. explain briefly, any link appreciated much)
2. Is it NOD32 cannot emulate sse1 correctly? If so, what is the detection percentage NOD32 is loosing? I mean, Are more malware present in the internet which uses this instruction.
3. If the above is true...Then is it really difficult to update NOD32 emulator to emulate sse1 instructions??

Thanks in Advance...
-Harsha