Adaptec 2410SA SATA Raid 5 : is it a safe choice

I intend to build a small server for my (6 Win XP computers) home LAN, to
backup my Data (and store some original documents).

Adaptec 2410SA Serial ATA Raid card seems to be a nice choice in terms of
price : you can use 4 cheap disks in Raid 5 mode to "secure" a capacity of
3. If I understood correctly, if ONE disk crashes, it's quit easy to
"rebuilt" its content with the parity data. Specially if a 24/7 capacity is
not that important...

I never built any Raid, so it's quite difficult for me to understand wether
it's a good choice in terms of real security for my data : what happens if
there is a "general" crash of the server (accidental reboot, no more AC,
controler Card burning...). Will I loose ALL the data of the array ? Has
the system a capacity to recover at least a part of data ?

And is the Adaptec 2410SA reliable ? Hard AND soft ? More than the
(cheaper) Promise FastTrak S150 SX4 ? Should it be better (and easier to
build) to boot the PC from another disk (I've got some small capacity disks
in my drawer...) and not from the Raid Array ?

Please help a newbie for a good choice...