|You probably can currently mirror to the 250GB. That would allow you to keep the RAID 0 array and still have redundancy. |
Another option is to use imaging software to create backup images to the 250GB.
BTW, the 80GB will only hold about 74GB formatted. Additionally, you need space to defrag and have a swap file. You should have about 25% for those two tasks. That would still put you in the correct range.
What do you do with the computer? There are some advantages to your current setup.