I'm currently finishing bug-testing a C#\Windows app that sounds like it fits your bill.
It is a lightweight trading platform that currently supports BTCe, Cryptsy, Poloniex and Kraken, with the plan to implement MintPal and Vircurex in the next version.
It supports all standard actions such as checking markets, placing orders, cancelling orders, checking balances and open orders. Also it has basic charts for all markets and a feature to set conditional orders(eg, sell at X if price rises above Y).
As well as encrypting your user details for the app, it also stores public keys using an enhanced SHA256 encryption and private keys via both a HMAC512 and SHA256 encryption. For even more security the only time your passwords exist in a plain text format is when you enter them for storage, from the moment you press save all data is encrypted and internally passed using SecureStrings. We even have a button to wipe all user data in case you ever fell you need to.
I have been using it for all my trading for the past week, and only problems I've had have all been to do with Cryptsy occasionally sending malformed headers, which just means you get an annoying pop-up and no chart
I've posted some screen shots here:
http://imgur.com/a/F2cnxIf you would be interested in helping beta test this, email me at
sidsoft2014@outlook.com and I'll put a get you a copy.