Wtf, seriously? Does your friend say that his P4 is better than an i5... Just because his got 3.2 ghz. Seriously, the ***? Your i5 may only seem to have 2.8 ghz because it have 2.8 ghz per core. The P4 is a single core CPU, yours is a 4 core cpu (sorry if it's dual core, i5 can have either and i'm too lazy to check which). This means that his P4 got 3.2 ghz and yours approximately have 2.8x4=11.2 but svar i've heard some of the ghz is post on a multi core CPU so let's say about 10. Now go brag to your friend!
And keep in mind, P4 sux nowadays and it is not nor whill it ever again be cool.