My Dad got me a set of these bits at Sears. Has all the security bits in it as well as the standard bits. Check out the [http://www.craftsman.com/shc/s/p_10155_12602_00947486000P?mv=rr|Craftsman 32 piece Security Screwdriver and bit set] for $25.
# '''Includes Torx® tamper proof: T7, T8, T10, T15, T20, T25, T27, T30, T40'''
# Fraction hex tamper proof: 3/32, 7/64, 1/8, 9/64, 5/32, 3/16 in.
# Metric hex tamper proof: 2, 2.5, 3, 4, 5mm
# Spanner bits: #4, #6, #8, #10
# For Triwing® screws: #1, #2, #3, #4
# '''For Torqset® screws: #6, #8, #10'''
# 1/4 in. sq. dr. to 1/4 in. hex adapter
I'd be amazed if it doesn't have what you need, but there are smaller sets:
* Start here: [http://www.craftsman.com/shc/s/p_10155_12602_00925702000P?mv=rr|6 piece bit set, Torx Security] $10.
* [http://www.craftsman.com/shc/s/p_10155_12602_00942614000P?mv=rr|Craftsman 7 pc. Tamper-Proof Torx Bit Socket Set] $30 (Probably not great for computer use.)
* [http://www.craftsman.com/shc/s/p_10155_12602_00942616000P?mv=rr|5 pc. Craftsman Tamper-Proof Torx Bit Socket Set] $40 (Again, probably not good for computers)
And if it comes down to it, you could try drilling out the security pin and using a standard Torx bit.