Why throw in the towel so easily? A quick Google search confirms your 1545 has a socket. Socket P. Whether you will notice the difference of an extra 100MHz and an extra 3MB of L2 cache is another question though.
Well, you said it yourself. I wouldn't really notice a difference. The extra 3MB L2 cache would be beneficial, but honestly I don't feel it. I might as well stick with what I have and then just get an all new system when I find the funds. So, about 5-10 years from now. Eh, whatever, my uncle stuck with a Pentium II 450 (he had that thing ramped up to positively screaming - 700 MHz! And 1 GB RAM!) for ~15 years until it died of a lightning strike, and if he can do it I think I can too. It seems that hardware is staying relevant for longer and longer as the bread and butter applications demands aren't really going up. Technically speaking the hardware in my lappy could be as old as 9 years old just as of now. It would have been hellishly expensive back then, though. Chrome just started requiring SSE2, and even that was an artificial requirement as SSE2 really does nothing for Chrome. It's just to check if it's there.
P5-133XL: Yeah, the RAM actually is
mostly worthless to me. Sadly, my lappy is maxed out at 4GB. Unofficially it could go up to 8GB, but why on a Core 2 based system? I don't find myself using more than half of my 4GB unless I'm playing something like TF2. Also, this is my most powerful system and I don't want to break it by doing explicitly unsupported things to it, otherwise I'll be stuck with a Pentium 4 until I can work up the cash to replace this one.