SATA versions are forward and backward compatible. However, that isn't going to be an issue in this instance because - at least from what I can find- the laptop doesn't use SATA. It uses a 44-pin Laptop EIDE Drive.
Unfortunately, these are not manufactured anymore, so sourcing a new replacement could be difficult, but not impossible, and may have a premium since being discontinued means demand is outstripping supply. getting a used drive is of course something of a gamble, too.
There is a sort of "underground" of users who keep systems of these vintage, and older, running and mixing them together with modern devices to get the best out of them. In this case, one option sometimes used is a CompactFlash adapter.
here. In fact, I have this very device in front of me right now. Effectively, what it does is allows you to use a CompactFlash card as a Hard Disk.
The astute observer might notice that since it's in front of me, it clearly isn't in a computer. Well- it turns out there are a bunch of little niggles and caveats with them that can cause issues. If you don't select the right CF Card, you can have issues involving it identifying itself as a removable drive, preventing certain things from working- These are the issues I encountered myself.
If you want to "clone" the existing install, that may prove difficult either way, because you need a way to use cloning tools while both drives are available- and their 44-pin laptop only EIDE interface presents a challenge. Another issue with that approach is that- at leasat as I recall- Autocad 2000's anti-piracy measures use the Hard Drive serial number information, so it wouldn't run on the new drive if cloned (but you can reinstall it).