Windows 7: Hard drive sizes...many small or one big?

I am currently running two 500GB WD hard drives for movie and show backups. I'm getting close to having each filled, so I will need new ones at some point. My original intention was to just stick with 500GB drives so if I have a failure I don't lose everything. However, this is looking like an expensive way to go considering I could have boughten a 2TB HD for what I have invested in the 500GBs...

All that and all my question really is is, are the 2TB drives reliable?...or do they have higher failure rates than the smaller drives?

For me personally, I would rather use a couple smaller hard drives than 1 really big one. You might want to get a couple 1TB drives. If you do go with large disks, use one externally and backup your data from your internal to your external. And if you can, keep the external out of your house...so in case of fire, theft, otherwise...your data isn't lost.