You mean windows 7 is faster better than windows XP as old emachine laptop? All new laptop use DDR3 ram memory is much better speed than old DDR2 ram memory.
Well...
1) expensive laptop with SSD is fastest boot up
2) laptop with 7200rpm HDD is pretty good boot up
3) laptop with 5200rpm HDD is not so fast boot up
BIOS? if you upgrade high performance RAM memory (1333 Ghz or 1600 Ghz) to replace standard RAM memory (1066 Ghz) must change volt from 1.5v to 1.8v in BIOS setting as improve bandwidth.