There is always something better...
If you waited to purchase for the next 'best Mac' you will wait forever. There will ALWAYS be something better later. Often you will get more for less. Its a fact of life.
I paid over $500 for a cell phone that was the size of a cinder block, had about 45 minutes of battery life, cost 2.55 a minute and that was 10 years ago. Technology changes, FAST.
So, does the iBook with Formac screen meet your needs? If it does, and has some room to grow (it does, you can add devices via FW, and add more RAM) then buy it. What you loose 10 months from now is bragging rights. What you gain NOW is a nice new laptop.
Remember, Macs from 1998 run Panther rather well. Macs from today, we can extrapoate will run new software fairly well in 5 or 6 years as well.
Good luck