just add a gfx card or tv tuner card for video input, and a sound card wich supports composite input
then buy a ps2, attach it and play
the cost of the card=around rs.10,000 total i guess
ps2,modded - around rs.12000
------
if u mean without a ps2, then its not really possible as ps2 emulation is still not fully possible
the emulators wich r dere cannot emulate properly and u cant actually play ne proper game wid dem
but u CAN play ps1 games using emulators like virtual gamestation and bleem.
no addtitional hardware needed for ps1 emulating...but if u want, u can buy a ps1 controller and a thing wich is available online wich lets u connect that controller to USB so that u can play on the ps1 emulators using a real ps1 controller
that controller USB converter is around 10-15 dollars i think