Nondeductibles are a massive PIA when you withdraw or convert to Roth (assuming you also have other, standard IRAs). Any withdrawal from a non-Roth is treated by the IRS as a withdrawal from your "one" giant IRA; thus, to take advantage of no taxation on your original contribution to the nondeductible account, you need to do a valuation of all non-Roths as of year end, then pro-rate the nondeductible contributions to arrive at what you are not taxed at. For example, we did small, placeholder Roth conversions this year (to start 5 year clock) and had to deal with nondeductibles that we made in the early 90s. After running the numbers, ended up keeping 1 or 2 % of the conversion from being taxed. (And, you'll need to keep your last form 8606 at hand until you withdraw/convert). Even if the nondeductible is your only IRA at retirement, you'll have to do this to enable taxation on your capital gains/accumulations in the account.
You should convert to Roth post-haste, particularly if you don't have other non-Roth IRA outstanding. The most tax you would then owe would be the gains in the account since you made the original contribution. If you have other non-Roth accounts, you would be subject to the pro-ration requirements.
To confirm what I've written above, you should become familiar with IRS Publication 590, your guide to IRA tax law:
http://www.irs.gov/uac/Publication-590,-Individual-Retirement-Arrangements-(IRAs)
Steve