It shouldn't cause any problems.
"Did it have all of the originalal toshiba software on it like when it was new?"
This assumption means nothing, let's say you buy a new windows CD it'll come 100% clean and won't have any branding of any kind nor toshiba's software (toshiba or dell's software should come in a separate CD too).
If They didn't give you a serial number nor charged you for a windows oem copy there's also the possibility they installed a dell windows oem disc and didn't validate it expecting you would make your own installation with the toshiba CD or you'd validate it just as you did which is as feasible as they installed a shared (piracy?) version of windows that had been branded by dell already. If the case is the first you should not worry at all, if the case is the latter there's always the possibility it has malware/spyware which can be fixed by removing everything and doing a clean windows installation with toshiba's CD