raid vs external drive

[hhhhbk]

currently debating whether to go for a pair of sata WD 500GB drives and raid them so everything copies from the one to the other

or to get a 500GB sata WD and also an external 500GB drive something like a seagate to manually back up to on a weekly basis

few questions

1
if a psu blew and took out one internal hard drive isnt it pretty likely it would also kill the other internal hard drive

2
if a virus got on a raid setup wouldnt it infect both drives giving both the exact same problem and lead to all data being compromised


im not sure if im missing something here as it appears that a raid system is a far from comprehensive method of backing up data

 

[hhhhbk]

thx for reply


http://findarticles.com/p/articles/mi_zdpcm/is_200305/ai_ziff41075

"You will also find adding or replacing drives easier with SATA. You won't have to power down your PC before connecting a new drive, because SATA allows for hot-pluggable connections, so you can add or remove SATA drives while your PC is running. "


got me thinking


DRIVE 1 500GB sata II boot drive inside the pc permanently powered up with windows and everything on

Drive 2 500GB sata II drive internally mounted which i only powered up when wanting to back up files manually from the first drive

just need some kind of switch which would turn the power off from the psu without risking damaging it by just pulling it apart... im sure it cant be that had to find



advantages

no cost of an esata enclosure

maintain the full sata II data transfer rate

no chance of it falling off desk . As the second drive only backs up this pc not being able to walk around from pc to pc is not an issue



DOES THIS SOUND LIKE A GOOD IDEA ???

does anyone already do it or am i overlooking something

.