new hard drive ,old bios …

i j ust put a new 30 gig drive in my machine. its only reading about 6 or 8 gigs of it. i know with the old bios it may not read the larger drives. i probably need to partition the remaining space. whats the best way to do that ? when i start from scratch and reset the primary partition, what values do i use for the secondary partitions ?? i dont know if the bios is flashable or replaceable. that would fix the problem.