A fast hard disk, permanent swap file and room for temp files make a big difference. The next thing is the video card. While this worked fine in the 386SX I used to use here, it really doesn't match the Pentium. There are a large number of video cards out there on the market. Some are fairly common while others are somewhat more exotic.
More video RAM costs more money.
The other differences are not immediately obvious. Some are Windows accelerators. In the same computer the ATI card is faster at every video operation and up to 10 times faster at some operations. So I got an ATI Graphics Expression card one day last week. This makes a serious difference in the speed of my Windows apps.