If the system locks up, then there is some driver/other issue. My most current systems do not lockup on all the fun hibernate/sleep/standby modes and perform these tricks flawlessly. I have a 5 year old system that can't do this, but it's 5 years old and without driver updates to fix it.
The LCD displays are fairly current designs and expect the power saving moves. Whereas the rest of the DESKTOP machines may not be so lucky.
All this is a personal choice to make.
I am running XP Home SP2 on a HP Pavilion 3.06 GHz. My monitor is a Planar LCD. The recent post regarding LCD life has raised a question in my mind. Bob recommends turning off the LCD after a period of inactivity. Should I also have the system turn off the HD and/or put the system in standby mode, or is this going to casuse a freeze up?