Here, the rule is that you cannot have enough and 64 MB is a good start. The third component is your video card where the situation is more complicated and there is not just one figure to be considered.
Some video cards allow to add extra video memory, and that's an option to be considered.
If you buy a new station, make sure your video card has at least 4 MB memory. So, that's the hardware part. For the most part, you want to stay with choices the software made for you, but no harm in experimenting a bit. However, bigger is not always better in terms of a browser cache. And while the ftp interface is convenient and allows for multiple file transfers via clicking and dragging, it is very slow and may not fully utilize the connection speed available.