I have a dell inspiron 2650 laptop that was bought 7 years ago. It did a fairly good job of serving me at the time. With nvidia GForce2 GO graphics chipset (hot at that time), I abused it with good amount of FPS games -- the keyboard mostly took the hit :). Now 7 years later, I was amazed to see it still surviving and running. All the important stuffs; motherboard, LCD display, CPU etc. are working perfectly. Considering how well it severed me, I decided to revive it. The following things were dead though:
1. Keyboard: This took the most hit. Arrow keys were non-functional, lost few key caps, and most annoyingly 'Fn' key was non-functioning. This means this keyboard was useless to control screen backlight. This was unfortunate because there is no software way to control screen brightness in this laptop. Cost: 20 USD
2. Harddrive was dead. But fortunately, I had a spare 40 GB, 2.5 hard disk lying around that was used as external usb storage. It was still in good condition for replacement, and had somehow previous ubuntu feisty installation (7.10) still on it. Cost: 0 USD.
3. RAM was 265 MB. It was good for the old time, but now it won't be enough to run GNOME desktop environment. Browsing around the net, I found that the max RAM it can take is 512 MB, in 2 DIMM slots -- each 256 MB module (it had 2 x 128 MB modules). A pair of 256 MB PC100 DIMM modules were quite cheap in ebay so I decided to max out the RAM. Cost: 20 USD.
4. Battery holds something like 20 mins of charge. Replacement battery with 4400 mAH cost 45 USD in ebay.
5. Power supply plug was broken (on the laptop side of the cord). The power brick itself was functioning quite well, but shame that the cord is directly hooked up from the brick. So there is no way you could upgrade only the cord (short of pulling it out from another brick). I decided to replace the whole brick. Cost: 20 USD.
6. CDROM drive was dead. Considering how little I use CD drive now a days (most things come from internet and my NAS storage anyways), I decided not to fix it.
9. Fan was quite noisy and active, indicating cooling problem with CPU. When I opened the laptop, I found good amount of dirts on heatsink and other places (no surprise :)). I bought a compressed air can and blow them out. Then followed by cleaning the fans with dry-wet cloth to remove sticky dirts. There were 2 fans, one for CPU heatsink and another smaller one for general laptop around the graphics heatsink. Another problem was that the thermal paste between the CPU and heatsink was dead dry and opening the heatsink invalidated it further. Bought a ceramic based thermal paste (those white ones) and applied it. Also, dropped a drop of cooking oil in the fans' hinges, just in case it helps :). Now they are less noisy and less active.
10. The LCD cover was cracked around the hinges. A bit of super glue helped there.
Software: Upgraded bios to A13 version (the last update from Dell) and upgraded Ubuntu over the network from Feisty (7.10) to Hardy (8.04) to Interprid (8.10) and then to latest Ubuntu Jaunty (9.04). The upgrades went smoothly except for few gliches in nvidia driver update. Apparently nvidia stopped supporting Geforce2 go in its newer drivers. The last support was in version 96.something. Suspend does not work in Ubuntu 9.04 (a known regression), but I managed to get Hibernation to work by blacklisting 'intel_agp' and 'agpgard' modules as suggested in some forums. GNOME desktop runs smoothly with all the compiz eye candies.
So overall I spend around total of 130 EUR by ordering the items from US ebay, shipping charge and VAT tax, to have a fully functional laptop. Not bad for a spec of P4 1.7 GHz, 512 MB RAM, Geforce2 graphics, 40 GB drive and brand new keyboard and battery.
Now it's as good as new :)