SiS 650 is a VIDEO chipset number, not a motherboard model number. Unfortunately, laptops (unlike desktops) cannot use generic drivers. They must use specific drivers from the laptop maker or special "hacked for laptops" drivers. Generic drivers will always fail install if any attempt is made at installing them. If this laptop came from Sharp with Windows XP installed, then it should have also came with either restore disks or a hidden partition on the hard drive containing the restore files. Also, Sharp should have drivers posted on their website. If they don't, you're most likely in a world of trouble. A notebook without the restore disks is worth about 5 cents (next to worthless). That's like buying a Cadillac without ignition keys or without wheels and tires on it.
If the notebook came from Sharp with some other OS installed like Vista or Win 7, Sharp offers no support for any os except the os they installed on it when they built and shipped it. In that case, I suggest you put it back in the same condition as when you received it using the restore disks or using the hidden restore partition files on the hard drive.
If that's not an option, then I suggest you contact Sharp tech support for further help. Then the next time you wish to buy a laptop, make sure it didn't come from some discount store as most companies that build them do not offer any support for laptops sold only through discount stores like Wal-Mart and PC-World. That's why they are so cheap.....
Brands like Toshiba, Gateway, Dell, HP, Compaq, and Sony purchased from Dealers will always normally have support posted on the laptop makers website. Sometimes, cheaper is not the best route to travel.
These links might be of help:
You should also check the manufacturers website to see if they have a chat or talk forum. If they do, then I'm sure your not the first person to confront this problem. If anyone else has done so in the past, they probably have discussed it on the laptop makers talk forum.