WinXP vs Epson drivers

We’ve recently upgraded our Win98 PCs to WinXP. We use Epson dot matrix printers on some PCs. Since the upgrade, our Epsons(LQ870 & LQ570+)do not print in the faster draft mode. They automatically print in the slower letter quality mode, regardless of the dip switch settings of the printer. Epson does not make dot matrix drivers specifically for XP. How do I fix this? I tried using XP’s Epson FX850 driver instead of the LQ driver. It then prints faster but some of the characters are illegible and too faint.