Rachel Bilson sassed up her outfit with high red boots yesterday in LA. The fashion-forward star has tried her hand at design in the past and recently collaborated on a jewelry collection that benefited a South African charity. Even though her stint on How I Met Your Mother will only be a short one, we'll see more of her getting back to those acting roots soon — her film Waiting for Forever is set to debut at next month's Santa Barbara Film Festival.

Drew Barrymore and Justin Long were out in LA together on Friday.

We're back with our latest fun quiz on PopSugar, where we're testing how well you know celebrity ages! The name of the game is 40 and fabulous, and we want to know if you can tell who is above or below the cutoff. From Jennifer Aniston and Angelina Jolie to Brad Pitt and Gerard Butler, it might be harder than you think. We've rounded up a gallery of big names for you to show off your skills — click here or below to play!

Carey Mulligan went casual for an afternoon of errand-running in LA yesterday, fresh off getting all dressy for the Golden Globes and the SAGs, though she didn't take home a statue at either for her work in An Education. It's not all losses for the newcomer this season, though, since she was just named Best Actress at England's Richard Attenborough Film Awards. Her boyfriend Shia hasn't been on her arm for any red carpets, but we'll see lots of them together when it comes time to promote Money Never Sleeps — there's a teaser trailer out for their movie already and Buzz has a sneak peek at what to expect from the anticipated sequel.

Olivia Wilde went with red at an Artists for Haiti event in LA on Thursday.

Halle Berry went casual yesterday as she headed into a meeting in LA. She keeps things simple fashion-wise during her day-to-day routine at home, but Halle can amp up the sexy when the situation requires. She turned more than a few heads with her low-cut and backless Kaufman Franco gown at the Golden Globes, and we'll see if she makes a repeat appearance at March's Oscars. Halle's red carpet style often seems age-defying — do you think you know her, Gabriel's, and other celebrities' ages?

Kim Kardashian stopped at a Beverly Hills nail salon on Thursday.

Cameron Diaz brought her big red Chanel bag along yesterday for lunch at Madeo in LA. She had a break from working on Knight and Day with Tom Cruise, which has taken up many of her afternoons so far this week. She was also busy earlier this month finishing up filming for The Green Hornet, but Cameron's had a little free time for other activities. She took a turn down the red carpet at the Golden Globes in a stunning McQueen gown, and she also caught up with her ex-boyfriend Justin Timberlake last weekend at the Hope for Haiti Now telethon.