Yes, honestly, your budget is too limiting right now. But that may really be a good thing. Recently there have been several new platforms announced and in production. but not available yet in the marketplace in quantity. With limited quantities the prices are likely to be high. As a little time goes on the prices will come down a bit and the manufacturers can fix any bugs. So waiting will actually be good.
I would strongly urge you, then, to wisely wait and save your money for the following:
1. Plan to get an AMD Duron processor in Socket A format - they are less expensive than the new Athlon Thunderbirds but will outperform the new Intel Celeron II's (which admittedly will probably be a bit cheaper). The plus is that you can later replace the Duron with a faster Thunderbird if you want to.
2. Plan to get a motherboard based on the VIA Apollo KT133 chipset and with a Socket A connector for the Duron or Athlon Thunderbird CPU. Don't get a mobo with a KX133 chipset or Slot A connector - they're yesterday's newspapers at this point. Watch AnandTech for a 'Roundup' of VIA Apollo KT133 boards some time in the future. AnandTech is tops for this kind of information - their reviews are kind of nerdy and way too long, but their conclusions and recommendations are reliable.
3. Plan to get as much RAM as you can afford - at least 64 MB, and preferably 128 MB. Be sure to get what is known as PC133 SDRAM. If you have PC100 SDRAM now it can still be used in the mobos I've specified to tide you over until you can upgrade to PC133.
Such a system will be a fine performer and likely have a longer useful life than others that are available right now too.
While you are patiently biding your time, read up on this stuff by visiting sites like AnandTech or Tom's Hardware, etc. If you get confused by all the choices (and who doesn't), try to review my recommendations above which can act as an anchor.
Good Luck.
P.S.
Watch AnandTech for their monthly Value Systems Buyers Guide articles. They only recommend hardware you can actually buy at the time. I think they will soon be recommending specific hardware of the type I've spec'd above.