I have purchased Dell inspirion 660s with core i3 processor. I have to install some softwares which can only be executed on windos XP 64 bit.
I tried many times to install windows XP 64 bit but was not successfull. Can windows XP be installed on this machine?
XP Mode is a 32-bit version of XP, so if your software requires 64-bit, you will need to install it separately as its own VM (with its own/valid/unused license).
Where are you getting stuck installing XP? BSOD 0x7b or no disks found to install to?
Note that, as stated previously, you may not get all devices functioning properly, as MANY manufacturers no longer provide compatibility with XP for their hardware. Also XP is end-of-life next year, so there will be NO MORE security and/or stability updates issued by Microsoft. You are better off moving to 7 or 8.
I can say you will find most/all of the drivers. Look for drivers beyond the dell website. Intel still makes drivers for Windows XP... Realtek does... Nvidea does.... And a lot of other ones do to.