lol, your post time was 9am... my post time was 3am... can you tell i was up late scouring the datasheet... lol

right... using the onboard PWM means i can set the frequency to what i want and not to the nearest xtal i can find, plus if for any reason i need to change it it's simple to do rarther than look for another xtal... and it makes floating point maths a little easyer!
To be completely honest, i skipped the section on using the tmr1 as a counter, and now realise i can link the PWM output into TMR1's COUNTER (not clock) input... so efectively, it was a stupid question...

resonators... cool, thanks for the info... i have one sat in a salvage draw I think it's 4MHz... and yes, i strip componants of dead boards, test then and re-use when needed...
anyone know what frequency the xtal is for the CMOS on PC motherboards?
I have a couple of these too but their no markings on them...

I suppose i could use one of my PICs to do a TMR0(20MHz) - TMR1(unknown xtal) compair, provided the xtals run TMR1...

Thanks Mell