Hi djhurio ,
Burning 700 mb is not actually overburning. It's just the 80 minute standard as you already may know. Most cd-re-writers can handle this easily.
Capacity of CD is 700MB or 734,003,200 bytes. Or even more 703MB = 737,148,928 bytes.
//edit// updated the info , apologies for the wrong information //end of edit//
In Nero , you can use the progressbar (below) to see how full your cd-rom is going to be. That's usually a good indication to check how far you can go. If you happen to write , say 701mb , it's not a problem for most cd-recordables , since almost every cd-recordable can overwrite a little.
You just have to enable this in the expert features and remember you can only use this option when you choose to burn " disc at once ". Don't forget to close the session.
Hmm crosspost.. let's close this one shall we ?