setup a fresh email account that you only use for poker and activate whichever double authentication factors the poker client offers, like getting a message with a code on your phone to allow login. also use a unique complex password for each poker site that you write down somewhere so you don't forget.
otherwise, to keep your pc free of malware, don't click on random stuff in emails telling you you've won a cruise or such, don't put your credit card details anywhere you don't trust (better off install a plugin called "https everywhere", it works on chrome and edge browsers), don't give anyone personal details like passwords and pin codes only you're supposed to know (you may get emails from scammers impersonating employees of various companies where you hold an account; never give away personal information, a real employee would never need to know them) and you should be just fine.
as far as a new laptop goes, shoot for 16gb of ram, an ssd and a competent modern processor, like a Ryzen 5 on Intel Core i5 or better. they come in different sizes (13.3"-17.3" displays) and thickness/weights , with or w/o a touchscreen, that's up to you to know what you want.
example:
https://www.amazon.com/HP-6-Cores-Gr...1&sr=8-20&th=1 .nothing fancy, you may find better deals if you shop around, I just ran a quick search on Amazon.