I put an SSD + 2GB memory into my early-2006 Core "1" Duo mac mini, and it's almost as usable as my 2010 Macbook (hybrid SSD/HD with 8GB) when doing light tasks (browsing, note-taking, iTunes).
Yes, the SSD is only SATA1, but that's still 4-6x faster on synthetic benchmarks.
Yes, the SSD is only SATA1, but that's still 4-6x faster on synthetic benchmarks.