hi
did you try to:
- disconnect the first ide hd
- connect sata one
- add the new hd to raid array via console
- let the array be in sync
- disconnect the second ide hd
- boot with SME's cd and choose "upgrade"?
this should leave unchanged your system but install GRUB.
when done, connect the second sata hd, add it to array, let the syncronization finish.. then, follow
this HTH
Ciao
Stefano