Hello, your best bet would be to clone your drive to an external drive, which will be bootable.
Get carbon copy cloner to make an exact copy of your old HD to the New one...
You're not likely to see any updates show up for 10.5.x
The very first MacBook 1,1s can actually run 10.6, which is updatable to 10.6.8, but will only run in 32 bit mode on yours.
Snow Leopard/10.6.x Requirements...
* Mac computer with an Intel processor
* 1GB of memory (I say 4GB at least, more if you can afford it)
* 5GB of available disk space (I say 30GB at least)
* DVD drive for installation
* Some features require a compatible Internet service provider; fees may apply.
* Some features require Apple’s MobileMe service; fees and terms apply.
Which apps work with Mac OS X 10.6?...
Buy Snow Leopard > http://store.apple.com/us/product/MC573/mac-os-x-106-snow-leopard
Call Apple Sales...in the US: 1-800-MY-APPLE. Or Support... 1-800-275-2273
thank you so much!!!!!!! finally i have a detailed answer to the question i have been asking my apple store ever since the macbooks became unsupported stepchildren. i am no expert by any stretch of the imagination, but even i knew i could not handle lion on this old macbook as the staff kept insisting. not one said just buy 10.6. so simple. i feel like such a dufus now. again thank u so much for just laying it out in such clear and concise terms. i wish the folks at applecare were as knowlegeable.