This is a two-part question:
1) My HP Laserjet 5000 manual does not prohibit non-HP memory chips to be installed in the printer. It only specifies using either EDO DIMMs or SDRAM DIMMs, and gives their part numbers. Of course, I want to just purchase top-name-brand DIMMs at the rock-bottom internet market prices. Non-HP memory is also available at higher capacities than their highest 32MB modules. I did this clever swap with an older HP230E inkjet plotter using SIMMs from my old Macintosh. It's been working fine for over two years. Will I get into trouble with the newer laserjets and the newer SDRAM chips? Of course I do not want to take HP's advice literally -- I'd rather get advice from third party experts.
2) What's the difference between regular 3.3v SDRAM DIMMs and 3.3v PC-100 SDRAM DIMMs? Their prices seems to be the similar.