That's how laptops work unfortunately. If they get old, you can't upgrade them, you have to throw them away and buy a new one, or use them in a state you acquired them, with old software and stuff.
You know, I'm writing this post from the second machine in my sig. It's ancient, has an Athlon XP, not too much memory etc. If I put anything newer that Windows XP on it, it would choke and die. I'm not too worried about it though. It can still do anything it could many years ago, and can use its full potential with old software.
CPU: AMD Phenom II X4 810 @ 3120MHz | RAM: Kingmax 2x2GB DDR2 800 @ 833MHz| MoBo: MSI K9A2 CF v1.0 (BIOS: 1.D)| GPU: Asus HD 6850 1024MB (DirectCu) @ 835/1135MHz | Display: L24FHD | PSU: PC Power & Cooling Silencer 750 Quad | OS: MS Windows 3.11 Pro x64