Whats the equivalent?...?

there is no equivalent processor ... the processors that u mentioned have quite different architecture and clock speeds..... a dual core is faster than a single core HT and a core2duo is faster than the core2duo running at the same clock speeds and for your second question the a dual core 2.0 would be about 10% faster than the 2.8 HT

Core Duo is better than a P4 even though the P4 has a higher clock speed. The Core Duo is like having 2 2GHz processors while the P4 is only one processor. The core duo architecture is better than the P4 anyways.

The closest equivalent, in performance, to a 2.8 ht p4 would be one of the new dual-core celeron processors. As for the Core 2 Processors, I'll use my e8400 for example. It's a dual-core processor running at 3 GHz, but when compared to my sister's Pentium 3.6 GHz, it's about 50% faster in single-threaded applications and about 120% faster in multi-threaded applications. Compared to a Pentium-D processor at the same speed, the Core 2 is about 40% faster overall. As for comparing a Core 2 running at 2 GHz to a Pentium 4 running at 2.8 GHz, the Core 2 will be about the same speed in single-threaded applications and 40 to 50% faster in multi-threaded applications.

ok the dual at 2.0 is going to be slower but has better multi tasking and if the OS supports multi threding it will run better. the 2.8p4 is going to be fast but your multi tasking is gratly limited by the FSB and the absence of another core. to tell you the truth get a AMD X2 they are cheep and they have a bigger FSB and to top it off you can get a AM2+ board and update to the Phenom lator