If you intend to deduct these expenses on a state return, be aware that you need a reliable method of determining which part of your computer and internet costs can be allocated to your investment activities. In this case, reliable means that it is written down or otherwise fixed into a permanent form (diary, notebook, spreadsheet, etc.), that the records were kept contemporaneously at the time of the activity (not guessed at the night before an audit), and the method of allocating expenses is reasonable. Is it really true that you use these items only for monitoring your investments? No Netflix, no email, no internet shopping?
Also note, the purchase of software and a computer must generally be deprecated over their useful life (probably 5 years), not expensed all at once. In some cases you can claim accelerated depreciation, but you must list the purchases as assets, rather than expenses, and let Turbotax tell you if you qualify for accelerated depreciation or to expense the asset. (Ongoing monthly expenses for internet access can be expensed.)
If you claim your computer as an expense (via an expense or depreciation), that may create a taxable event in the future if you sell it, even as used. For example, if the computer cost $1000 and you claim $700 as a deductible investment expense, your cost basis is now $300. If you sell the computer for $400, you have $100 of taxable income (depreciation recovery).
