since I'm using winxp home1a (oem through newegg), the SATA drivers are already on the cd right,
No, you still have to use the F6 floppy combo to install the SATA drivers provided by the board's manufacturer. The OEM WINXP disk you have, only has SP1a installed, not the additional RAID/SATA drivers, the MaxPC article was doing a custom driver setup in addition to adding SP2.
should I even bother slipsteaming sp2
Depends, If you have the XP2 cd and don't have to download it everytime you reinstall, it's not that bad. If you do have to download it, you risk going online without some of the security features that are installed with SP2. You should also be aware that the SP2 slipstream won't work on some OEM disks, so it may be a dead issue anyway. Either way, I would still get the free SP2 CD from Bill Gates Is My Daddy