150 max is what you would get. Like I've said before, try selling it at a local college for 150 bones and call it a "good internet computer" The poor kids will dump 150 bucks on it no problem because they need a computer and still need cash to buy their mac N cheese.
Win98 sucks and that would be mean to take your copy of XP off there but once again, if you're going to sell it for 150 bucks, you might as well keep your XP.
And it depends on what kind of monitor. I would keep the monitor so you don't have to buy a new one.