Is Susan still a cutie?

This question, featured in a hard-to-miss ad for Classmates.com (search), beckons the lonely and curious to track down their former high-school and college flames — who, thanks to the Internet, now seem just a mouse click away.

"There's so much on TV now with people trying to reconnect," said Oregon relationships and sex therapist Alexandra Myles.

But is hooking up with your ex a good idea? Two new books give opposing answers.

In the upcoming “My Boyfriend’s Back: Second Chance Love,” Donna Hanover (search), the ex-wife of former New York City Mayor Rudy Giuliani (search), says the first cut is the deepest.

“These couples often find that they see each other through young eyes, that they trust each other almost instantly, and that their love is more profound than they ever imagined it could be,” Hanover said in a statement issued by her publisher, Hudson Street Press. The book is slated to be released next Valentine's Day.

Hanover, who married her high-school sweetheart Ed Oster after divorcing Giuliani, writes about other couples who reunited later in life, and how having a past together can enrich a relationship.

But Susan Shapiro, author of the recently released "Five Men Who Broke My Heart," (search) a first-person account of digging up old boyfriends, says the high-school yearbook can be a Pandora's box.

"You can hurt yourself, break up whole families," she said. "One [married] ex was so angry I looked him up he told me he'd rather take out his own appendix than see me."

Still, hearing the fairy-tale stories of those who did rekindle old flames makes the temptation hard to resist.

Lucy Hodnett says she was just about ready at 38 to become a "wicked old woman with cats" when she reunited with her high-school boyfriend on Classmates.com, a Web site that helps people reconnect with old school friends.

"He will tell you, and I will tell you, that the moment we saw each other again, we knew we would always be together," said the North Carolina resident. "It's amazing how nothing had changed — we're wiser, more mature, but the same people."

Her new, and old, beau David was a month away from being divorced when Hodnett found him online.

David Treannie of Oklahoma also found his ex-girlfriend-turned-wife, Sue, on Classmates.com.

"I was single with two kids, just trying to figure out the computer," Treannie relates. "I went to Classmates.com and saw my wife's name. We got to talking — she was single with three kids and also divorced. We got married eight months later."

But in spite of the success stories (more widely reported than the failures), Myles says the probability of a reunion working out is very small.

"People move on and shift and change," she explains. "What we were like as teenagers just isn’t the same. What most people are trying to do is go back to a fantasy they held about being in love, about romance. It's rarely a sustainable connection."

Shapiro, who was married when she unearthed her exes, thinks there are some situations in which looking to the past for love may be worth a shot.

"If you’re single, and there’s somebody in your past who you thought was really good and you trusted, but you thought you were too young to get married, like Donna Hanover, then do it," she urges. "Hanover went to a reunion and found true love."

Shapiro says Googling, attending reunions and sending holiday cards can all be good ways to reconnect.

But if not much time has gone by and you're just a little lonely or bored, or if the person you're thinking of contacting was a jerk at 17, Shapiro says it's better to let sleeping dogs lie.

“It depends on how much time has passed — I saw men I hadn’t seen in 10 to 20 years," she says. "If it's a year later and you're still angry, you might as well stab yourself in the knee. You have to be in a different, emotionally open place."

Shapiro also warns people not to set their expectations too high. Just because one person still harbors feelings for a former love doesn't mean that the object of their affection will reciprocate.

“You don’t want to barge in and be a stalker," she said. “You can’t attach fantasy to it, especially because that person went on with his or her own life. Don’t show up with flowers and candy, or in a negligée. And remember that people don’t look the same at 53 as they did when they were 17.”

But Treannie begs to differ.

"Sue looked exactly the same 24 years later. It was like meeting up with each other in the sand pits again," he said.