Very decent color chart...

[Ronzi]

I suspect you might want to decide which colors you definately do not want, then look for the others and be ready to compromise a little.
For example, if you do not want silver, black, blue, or red, you have eliminated about 75% of the of the available cars already. The percentages of colors that you will see in the color survey on this site match pretty well with the real world. Silver is noted as the color for 29% of the 169 respondents vs 26.5% in the 1,070 Boxsters available on Cars.com.
As you have noted, there is silver, and then there is Arctic Silver. I agree you can't tell much by looking at pictures on web sites. They don't really show you that Arctic has a subtle blue cast to it vs the whiter shade of some of the other silvers. You 'bout have to see them for yourself.
Plus, there is the factor of what was a standard color in '04 was not a standard color in '01. So if you particularly the like Basalt Grey (not necessarily a real color) you saw in the showroom on a new car, it may be virtually nonexistant on an '01.
Good luck.