The hard drive recently died in my G4 Cube, so I just purchased an IDE SSD. Like you do.
The CD-ROM drive died a few years ago, so, as it were, I have an unoccupied IDE connector in my Cube. In theory, I could get a second IDE SSD and then I could use softraid to RAID-0 stripe them for extra speed. Considering the IDE bus would almost certainly be my throughput bottleneck even with only one SSD, that would be pretty useless. On the other hand, who else among you has a G4 Cube with striped SSDs? Anyway, no question here, just enjoying the fact that this old machine can still run modern software thanks to the effors of this community. Perhaps, I may even do something important with my Cube and RAID-1 mirror the SSDs for redundancy.