Windows 98 xp drivers , possible? multiple Qs

Hello there I have an old pc at my house that runs on 900 mhz , 256 ram .. so forth. it has windows xp on it and runs dreadfully slow. at first i thought i would up the ram to 512 to smooth things out but . even though it says on the web the max ram is 512 i put the second stick of ram in and it comes up with a screen saying i need somekind of updated bios .. however when i write down where to go .. its not there. lol . its an old hp wallmart special originally designed for the "cough"crappy"cough" windows me. i put the xp on it .. lol {dont ask}
so i figured i would install 98 on it and watch it fly. but i want it too be a little bit smarter than your average computer with 98 . is there anyway i can take drivers that come with xp and have them run on 98 as if it were the same. and if it were posible .. would that just defeat the purpose of switching to speed it up in the first place.
also: does anyone know of a good "free" program to make it look like xp .. i wanted to do that as well if its possible.
well any help would be appriciated . thanks
mako