Pentium 4 Hyper Threading

Recently we got our CPU
(P4 /2.53MHz /768Mb RAM /80Gb HD)
replaced with another
(P4 HT /2.6MHz /1024Mb RAM /160Gb HD).
I can see that hyper threading is activated in BIOS otherwise I can’t see much difference. The only difference so far is that I am able now to install SpywareGuard 2.2 where I wasn’t able to install it on the previous machine no matter what suggestions mentioned on forum pages here. So, what HT supposes to do and how can I see it working practically not theoretically.
Thank you

 

have a read here(dont know if it explains what you want!)
http://www.intel.com/technology/hyperthread/index.htm?iid=sr+hyper&
or here
http://www.intel.com/cd/ids/developer/asmo-na/eng/microprocessors/ia32/pentium4/hyperthreading/index.htm?iid=sr+hyper&

 

thanks.
I know this stuff is theory. I wanted someone who has tried hyper threading to yell me about his opinion, the differences, and can these differences be felt in practice. Any one please.