Just insert the card and go to Network Prefs. Setup a new network location that turns the card on and turns off the internal card. That worked quite well for me.
Just be careful to withdraw the card while you're transporting it. The plastic antenna portion that sticks out of the slot can be bent much too easily.
And that Wavelan Silver will only be giving you 40-bit WEP, might as well not have any protection on your wireless access point. Way back when, I found an 11-g card for very cheap, $25 at Target. There may be similar deals out there nowadays, especially if you're going to be using this for awhile and are concerned about security on your wireless access point.
Taking the card out is quite a hassle, since you have to take the bottom case off. Which in itself is not hard, but you inevitably want to use the feet on the bottom case to position the case for putting the screws back in, and you risk ripping off the bottom feet--a problem if it's not yours.
And if work wants to eventually give that Ti-800 away, it would be quite useful to a high-school student or even an elementary student. (edit: it's a Ti-800, natch)