can anyone suggest a good simulator that can simulate PICs as well as the circuit before the PIC??

 

Try Oshon softs PIC simualtors anyway I find hardware debugger like ICD is a better way...

http://www.oshonsoft.com/

Good Luck

 

You have also the proteus VSM. Not free, but You may trail it for 30 day I think
http://www.labcenter.com/products/vsm_overview.cfm

 

I came across some software called Yenka. Its relatively simple but you can add an array of different passive and active components and it supports some PIC and PICAXE chips.
www.yenka.com

 

you can use RealPic simulator...