There's no mention of manufacturer and/or model there ... so it should be obvious i can't say for sure
i figured you'dbe smart enough to remove the side panel and LOOK with your eyes at what is written on the power supply label
still it says up to 90% efficient (80plus gold) and most of these power supplies are modern and have most power concentrated on 12v so you should be fine.
one more thing: that power supply may not have a pci-e 6pin power connector. If your video card will require one you may need to buy a molex/sata to pci-e 6pin adapter cable ad hope the power supply has spare connectors.
ffs open the lid and look iside and see what power supply connectors are present and unused if you plan to buy card that requires extra power connector
I would buy the GPU and install first. Worst likely thing that could happen is that the system will not start up due to insufficient power. Worry about replacing the power supply only if you have to. Dell's pretty good in terms of how-to guides when it comes to replacing parts as well.