Working on an ATX

I know that with an ATX system you are suppose to take the power cord off before working on it but is it alright to flip that physical switch that is on the back, on the pwr supply instead? That way, it is still grounded.

Just one other question: How much would you sell a brand new custom built computer (by me) for? It has:
-cool traslucent case, 300W pwr supply
-Sound Blaster Live! value
-TNT2 Vanta based video card
-20.5 GB Maxtor HDD
-MS Internet keyboard, MS intelliclick mouse (wheel)
-Samsung floppy disk drive
-Abit ZM6 mobo
-celeron 533
-no monitor yet (might not include one)

Thank you

Yes you can work on an ATX system with the main P/S switch turned off. But it is a whole lot safer with the cord pulled. That way you know it's off for sure.

I would have to agree it is far much safer if you unplug it first. who knows what could have happed to the ps