THEY ARE AWESOME !!!
Have two of them, and they work with ALL games. Quite expensive, but as you say if you already have the PSX controllers, they are the BEST controllers ever made!!! IMHO
http://www.ccl-uk.net/
Get the Smartjoy 3s as they support Force feedback and work with PS2 controllers as well as PS1.
I use a Sony Dualshock and a Hori Fighting Stick (Arcade machine style) to play Mame ( http://www.mameworld.net/ ) games with. They work perfectly. I use Win2K SP2 and DirectX 8.0. Comes with a driver CD for both Win9x and Win2K. Also the drivers are very good. Full graphic of the controller and all the buttons. Also, allows you to test out the force feedback in the control panel.
ABIT KT7A-RAID zt Bios
Enermax 350W PSU
Tbird 1Ghz@1066 266 FSB
512MB (2x 256MB) Crucial CAS2 PC133
Gainward Geforce 2 PRO 64MB
IBM 60GXP 60 gig IDE 0 (Ultra DMA mode)
PLEXTOR 1210A CDRW IDE 1 Master (DMA mode)
TOSHIBA SD_M1402 12x DVD on IDE1 Slave (Ultra DMA mode)
SB Live 5.1 Player
3COM 3C905B-TX 10/100 NIC
Netgear FR314 Cable Router/Switch
SONY G420 19" monitor
Intellimouse with intellieye, on Ratpadz mat
Win2k SP2, NO ACPI, VIA 4.29v Drivers + USB filter v108
2x 'Smartjoy 3' PSX adapters + Sony Dualshock