Old specs:
Soldered SX-25
4MB of RAM
integrated ET4000W32 local bus graphics
No sound card
No hard drive
No DVD/CD-ROM
Normal floppy drive

New specs:
80486DX2-66MHz
16MB of RAM
integrated ET4000W32 local bus graphics
SoundBlaster Pro 2
DVD-ROM
CF as hard drive, and a floppy emulator.

When I got the system, it only had 4 megs of RAM. Luckily the guy who gave it to me also bundled in some more RAM, which turned out to be 12 megs.
Luckily the CMOS battery hadn't corroded anything around it, so all I had to do was snip off the battery, connect some new batteries to the onboard battery header.
I also upgraded the SX-25 to a DX2-66, which made a large improvement. The graphics card was a surprise, because I didn't expect it to be a local bus model, most of these Compaqs had ISA graphics. Another surprising thing was that the graphics chipset was the W32 model, not the earlier AX.