if you mean replacing the cpu with another, then its limited by your motherboard's design, if its the one listed in the ebay link, then it is Slot 1 capable of a Pentium III at best, but no guarantee of that fact or the speed it can support.
Big differences between Pentium II and Pentium III?
Pentium II had a fsb speed of 66/100 in its models
Pentium III had a fsb speed of 100/133 in its line of Slot 1 CPUs
Pentium III has a faster clock speed except its slowest model compared to the Pentium II's fastest model
Pentium III's support the MMX and SSE instruction set. while Pentium II's support just MMX
Pentium III's with the Katmai core, like all Pentium II's had 512kb of cache which ran at half the speed of the processor
Pentium III's with the Coppermine core, had 256kb of cache on the chip which ran the the full spped of the processor (even though less, was better in performance)
Pentium IV's never existed for the Slot 1 platform.