The expansion slots are rated for multiple insertions and you get a thicker board with stronger traces that are less likely to crack under repeated flexing. Dual heat sinks and 1 or 2 high capacity ball bearing CPU fans are the minimum required. Request that your supplier flash the BIOS with the latest release upgrade before shipping. Get a built in 512k pipeline cache, AGP port and Universal Serial Bus support. Look for multi-voltage and speed selection to accommodate future CPU upgrades.
Speed is everything.
Go for 800MHz or faster. Get 700VA capacity or better. Don't take your computer case for granted. It can be the source of Gremlins when you choose the wrong one. Most computer cases are negatively pressured, meaning they exhaust more air from the case than they take in or make up , which creates a vacuum in the case.