If you want to speed up your Windows XP without the internet and the network connection then you have to do one best thing is defragment.. You can defragment your windows XP from control panel > disk management > right click on drive > defragment now..
Goto my computer > right click on drive > propertis > tools > defragment..
From this process your XP will process speedily and also you have to scan the XP with antivirus daily to speed up your XP......