Obviously, converting your $100 to bitcoins incurs an expense, and then if the recipient wishes to convert those bitcoins back out to USD further expenses are incurred. So using bitcoin simply as the payment network does cause some of the value to be lost. But then again. the same goes for a payment when Visa/MC or PayPal is used (for a commercial transaction).
If you are in the U.S., you can take your $100 to a
Bank of America or a Wells Fargo
Chase Bank and deposit that $100 into the bank account number provided by
ExchB ( https://en.bitcoin.it/wiki/ExchB#Bank_Branch )
Then subtract the minimum $1 deposit fee and you left with $99
You will then have USD in the account to buy bitcoins with.
After you have bitcoins, you can then withdraw those to your own bitcoin address (from your local bitcoin client preferably, or from a mobile app or an eWallet service even) and then from there send those bitcoins on to whomever you wish to pay.