Gx110 cpu upgrade

Here is what I have;

1 Dell Optiplex GX110, 9/12/2000, CPU -(80526)733mhz, 256KB, 133 FSB,Bios AO6, 810e chipset, 256 MB SDRAM, WIN 2000 PRo. 52x CD-ROM, All standard harware (will be installing ATI Radeon 7500 Vid. card).Low profile.

 

1 Dell Optiplex GX110,4/18/2001,CPU-(80526)933 MHZ, 256 KB, 133 FSB, Bios A06, 810e Chipset, 512 MB SDRAM, Win 98se, ATI RADEON VID. CARD, 52x32x52xCDRW.,52xCD-ROM. Mid-Size

 

1 Dell Optiplex GX110, 5/17/2001, CPU-(80526) 866 MHZ, 256 KB, 133 FSB, BIOS AO7, 810e Chipset, 384 MB SDRAM, 52x CD-ROM, All standard hardware (will be installing ATI Radeon 7500 Vid. Card). Low Profile.

 

I need to know how fast of a processor I can put in these systems and what I need to do this. I have read alot about this and have found conflicting answers. I have found the upgrade can be 1.0GHz to 1.4 GHZ. I have found that I may need an adapter. What do I need? Coppermine w/out Adapt. or Tualatin w/Adapt. I am pretty good at computer stuff, but need some help in making sure I get the information before I buy. I can't afford 3 new computers. I also like the ones I have.