for 80gb hardisk?

how much should i form for primary partiton c drive and extendend partitons to be precise d and e. is t what is the size in gb i should create.

for 80gb hardisk?

depends on what D and E will be used for? Other Operating systems? backup backups should be big ample to hold all of your primary programs near out the downloadable programs. The programs the computers came next to.
divide it into thirds, one third of the harddrive for each drive.
resourcefully since 80gb is a rather small sturdy drive these days i would merely split to 2x 40gb's, since splitting it 3 ways since 26.7gb per pairtion is rather small.