I have a new notebook which is an r519. I have no idea how to split the drives and which percentage should be which. I've been sitting here for ages moving the slider then moving it back. The total harddisk capacity is 232.88gb. How should I split this between C and D drives
Assuming you want to put the OS on the C drive and the data on the D drive, then size the C drive to hold the OS and your applications and the D drive for the rest. Depending on how many applications you have, 60 to 100GB is probably adequate for the C drive.
There's no law that says you NEED two parititions - you could also use just one large partition for everything. The biggest reason to use a separate C: partition for the OS is to reduce the size of an image backup of the OS. If you don't plan to do image backups of the OS then you may not need separate partitions at all.
If you're very careful about how you distribute things, you can use partitions to improve performance. But given your question I think it's probably simpler for you to use as few partitions as possible.
A lot of notebook computers have a "recovery" partition which can't be deleted or changed. Such partitions typically contain stuff that allows you to recover from a trashed OS. That's separate from your other partitions and shouldn't affect how much you allocate for the OS. In other words, my comment of 60 to 100GB depends only on how much space you're going to use for the OS and applications, whether or not you have a recovery partition makes no difference.