Technically there is absolutely no problem with what you propose.
Personally, I use Partition Magic to firstly create the partitions and then it allows you to actually choose the drive letters you want for the particular partitions.
It will even run software to trawl through your computer changing the 'old' drive letter to the 'new' one.
I'm not sure what software comes with a Maxtor drive these days (I too am using two Maxtor drives but only 30/20Gb - can you imagine saying 'only' five years ago?)
Maxtor drives certainly used to come with Maxblast on them to allow partitioning and they still talk about the latest version on the Maxtor web site, so presumably they do.
What I reckon is, without intervention, all the drive letters will shift 'to the right'.
Still, not sure about that. PM can definitely sort it out for you though.
Nero only detects the letters assigned by the Operating System, but will pick out the CD/DVD drives.