Depends on what you do. for simple web browsing, word processing, spreadsheet, etc. having a 66MHz bus won't really be a big bottleneck. It's when you start doing web servicing, 3D stuff, or apps that require a higher system bandwidth that it becomes a bottleneck.
If you do get a brand new Intel based system, of course get a 133 MHz fsb board. Generally the most popular solutions these days are ones based on the i815 chipset and VIA Apollo Pro133A. If you're one of those people that like tried and true technology, the BX133 platform is also a possible solution. However, be aware that AGP on any of the BX133 boards are overclocked.