The 2 most important drivers that you must install are the chipsets driver and display card driver. Otherwise your PC won't work properly or will even run very slow.
Enabled DMA will make harddisk run more efficient and hence faster. To check whether it's enabled or not, just go to device manager and select disk drivers and then properties.
When you install Windows, it will create/delete/re-create/delete many temporary files which will result in files defragmentation. So I suggest you perform a file defrag after Windows is installed and before any software is installed.
For Win XP, you should only use NTFS. There's no need for FAT32 unless you want to dual boot your PC with Win9x/ME.