Don't forget to check with local cable suppliers, they're cheaper than the box stores.
Bruce is right about the stranded issue, you don't want to be using stranded wire with anything other than the sort of connectors designed to support it. Most aren't, as they expect to be used with solid core wire.
As others have responded, there's no pressing reason to use shielded CAT5 for computer networking in a home environment. Shielded CAT5 is appropriate for industrial applications with very high levels of electrical noise such as a factory with arc welders.
There might be some benefit to shielded CAT5 for CAT5 cabling that is pressed into service for analog (not computer) applications such distribution of low-level (not speaker-level) audio. IME, surplus shielded CAT5 is less expensive than 4-pair with shield audio cable but doesn't provide inter-pair shielding.
Another property of shielded CAT5 that might be either a plus or minus is that it is mechanically stronger (it can be pulled harder without damage, better abrasion/cut resistance) but is less flexible -- so you do have to pull harder ;-)
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